Just me rambling...not sure if I'll get finished in this post but I'll give it a whirl, and maybe it'll help some understand a little better.
Yes, surface area (direct coil to juice contact) has much to do with vaping. Higher resistance coils usually have either fatter wire (diameter, but with a higher percentage of insulating material [ceramic clay just as as an example] in the metal), more wraps (length) or both

Either way, that means more surface area to come in contact with liquid and turn it into vapor. So even at lower temperatures, lots of surface area can help increase vapor production. Dual Coils use this very principal in that we actually use lower real temperatures but spread the heat around more in the cartomizer.
OK, electricity is a little different from fluids in how it is 'conducted' through 'conductors' or blocked by 'insulators', but these basic Ohm's Law ideas help people begin to grasp the concept.
Volts: Think of this as a water tower sitting on the hill. Several things about a water tank are worthy of notice. How high the thing is off the ground (gravity induced pressure), and how much water it will hold (capacity) give us forces to use to move all that water from point A to point B. The higher the tank is, the more pressure it can provide to any pipes connected to it, so think of volts kind of like the hight of that water tank.
Mah (milliamp per hour): Think of this in terms of how big that water tank is...how much water it can hold.
Amps: This is the current. Think of this as 'how fast' the water moves through a pipe or a hose.
Resistance: Think of this as different diameters and lengths of pipe, as well as valves and nozzles, that will carry the water from the tower to a tap a mile down the road. Greater resistances can slow the water flow down, but it can also increase the pressure or intensity throughout the entire system. Lower resistances can dump alot of water really quickly, but they might not have as much pressure or intensity/control behind them.
Now consider your garden hose at the very end of this system, and picture a high pressure nozzle verses no nozzle at all. You should already be able to visualize how opening the tap to full and changing the nozzles can effect how fast the water shoots out of your hose, and how this effects the length of time it takes the tank up on the hill to become empty.
For this analogy, we also have a bucket that we will be filling with that water hose, and for now you can kind of think of this empty bucket at the other end as watts. We want the perfect setup to fill our bucket to just the right level in the perfect amount of time for our application.
By changing the pipes, hoses, and nozzles (resistance), we can take the same voltage in that water tower and have it fill that bucket at different speeds, and with different intensities of force right? If we are not careful, we can even arrange things so that the system dumps water so fast the pipes burst (pop an atty), or even cause the water tower to implode (catastrophic battery failure).
Watts in a Darwin: In electronics, watts generally refers to dissipated heat, but in the case of the Darwin speak, it really means a calculated POWER that the battery will be regulated to supply to the atomizer based on the variables of Ohm's Law. Ohm's Law can get us a 'consistent power' delivered to whatever atomizer is screwed on, and this is the foundation of how the Darwin is designed. This is not to say Ohm's Law covers everything that can effect the over all vaping experience, as it clearly can not explain things like the vapor point of various liquids, how coils go about heating the liquid, how air is drawn through the atomizer design, the efficiency of wicking systems for the e-liquid, and so forth. This is why the Darwin makers call it 'Adjustable Power' instead of watts, or temperature, etc.
For most PVs, the water tank at the top of the hill is an assumed constant (3.4 volts as an example), as well as the size of the pipes and nozzles (resistance of atomizer); and, the current is what you alter the most according to how much resistance is applied in the atomizer that you attach. Some PVs go to all sorts of simple or elaborate tricks to keep the 'current' from getting so fast it fries things or implodes the battery, and in some respects the Darwin is among them. In general, current (amps) is the dangerous part of electricity. That is when it is motion...kind of like water flowing over the turbines of a dam.
Lower resistance atomizers heat up very quickly, they also cool off relatively quickly, and they also ask the battery (water tank) to dump out energy faster (amps or current). In the water analogy you might think of this as a really large pipe that lets the water dump out really quickly.
In electronics, the concept of current is quite similar as our water system described above, but the material ratio is usually the opposite (bigger diameter or longer coils can have a higher resistance...the extra size is added because 'insulating materials' are added to the alloy to allow fewer electrons to flow through them, or they just make it bigger and/or longer thus slowing down the current...and while insulators or extra material can slow down the current, they can also absorb and store lots of heat, so they can take longer to both heat up, and to cool off).
In the Darwin, we think backwards from other PV systems. VV systems focus on the height of the water tank, and may have a pulsing or shutdown system to prevent dangerous currents, and that's it. Fixed systems focus on changing the current via swapping the resistance of the atomizer, and maybe a pulsing or shutdown mofset to keep current under control. The Darwin uses a simple computer and Ohms Law to constantly regulate the voltage, and to some degree the current needed to arrive at your 'power setting' (Or the Watts variable of Ohms Law). So, with the Darwin, the user focuses simply on what setting gets the 'bucket full' the best for his vaping application.
So after soaking on all that, what's really going on in the Darwin?
You control the Power with your wheel (Watts in the
Ohms Law formula).
The resistance is supplied by the atomizer system you screw on (Ohms).
The atomizer system by nature asks for a certain current (amps) depending on the voltage that is available to it.
And the missing variable, Voltage, is calculated via Darwin using your power setting and the atomizer resistance, using the Ohm's Law formula (In this formula the Power Setting represents Watts).
One thing worth noting, is that the Darwin limits itself to somewhere around 3 amps of current (may vary with your particular Darwin) as the maximum safe current. This is to prevent permanently damaging the chemistry of your battery (which could result in a battery fire), and also is still a safe current in the extremely rare event a spark somehow arcs to 'shock' the user. So even if your wheel says you can still crank up the power but you notice the Voltage and Amps refuse to go up anymore (and the Ohm's calculator on Google no longer matches up with your estimates), this is why. The Darwin's safety circuitry has kicked in at the 3 amp limit. You can ease the wheel down bit by bit until you find the 'true power' being supplied again (when the voltage or amps start nudging down again). As an example, when I screw on a 2 Ohm dual coil, my Darwin maxes out at around 5v, 3 amps...even though I can still turn the power wheel up quite a bit.
So is it true that vaping with higher resistance atomizers will make your battery last longer?
Honestly, that all depends on how you like to set the power, and how long you burn when you draw. Also, we have to remember that batteries (PVs in general) are chemistry based, and things like the temperature of your room, the altitude and humidity, or even the phase of the moon can impact their performance in some way. So it's hard to say for sure my Darwin will work exactly like yours when it comes to battery efficiency.
For me, it is very much true, but I like higher resistance gear at lower temperatures. I also live pretty close to sea-level in a high humidity area. I can get high enough temps to vape like a research monkey with a very small trickle of amperage. In a similar light, this is why if you go to the camping goods store to shop for an electric lantern meant to burn all night...you'll notices they tend to come with bigger, higher voltage batteries who's bulbs have higher resistance elements in them (they usually take a while to warm up to full luminance, and can even dim out slowly long after you've cut them off). Lights meant to flip on and off frequently for short periods of time will have lower voltage batteries with lower resistance bulbs in them.
On the other hand, if I crank my Darwin up to the kinds of heat that LR atties are designed to deliver very quickly by default, that battery efficiency gap starts to close...in come cases, for things I prefer to 'vape hot' I might be better off with LR at lower voltages. It all just depends on what you want the vape to be like
Is it true that LR stuff isn't as good on a Darwin?
If we're talking dual or triple coils...not at all...a whole different ball game. Those use more than one high resistance coil and spread the heat around differently.
With single coils...again...there is no rule that says HV gear is better or worse than LR....it all just depends on your tastes and prefs for throat hit vs flavor, and so on.
LR gets hot really fast, and it cools a little faster than HV stuff. LR also usually has less coil to wick/liquid surface area, but given good enough wicks kept nice and wet the higher temps can still pour out the vapor at very high rates. LR also runs the current (amps) up more quickly if you like higher settings. It is also harder to get LR atties to work at lower temperatures. I've seen some that just won't burn cool on my Darwin period...3.8 Volts is as low as they'll go, even tho' the wheel has a few settings downward (some times as much as two full watts) left in it. In contrast, I've had some higher resistance atties that can barely smolder at 3.2 volts on the Darwin (I don't use it turned down that low...the point is just to explain that some LR stuff isn't going to burn any cooler than 5, or even 6 watts unless you find some sort of low voltage battery below 3v with an abnormally high capacity and c rating, or put a bunch of extra circuits or resistors in the mix somehow...).
For the most part...don't worry about the battery life too much. It's going to be pretty darn good no matter what you screw on. Get what you like and set it how you like it
