The Darwin goes up to 12.7 watts which is where most people who use dual coil cartos set the Darwin for. It max's the voltage out at about 4.6 volts which is right in the "sweet spot" of 4.5v - 5.0v that most vets find as the prime vaping level for producing warm vapor with no burining of the eliquid. I've never burnt any eliquid ever vaping at 4.5 - 5 volts. Just nice warm, full vapor with excellent throat hit.
I fully agree the Darwin drives the dualies superbly.
I need to attempt to clarify what I mean by a Darwin 'showing' 12.7 on the power dial doesn't necessarily mean it is delivering that much power:
With higher ohm dualies (2 Ohms and up), it IS possible to consistently put out the full 12.7 watts of power before the amp ceiling is hit. (3amps, 2 Ohms, 6volts, 18watts)
If the power wheel would go that high, you could actually achieve up to 18 watts before hitting the amperage limit. It doesn't go that high, because someone just might get burned pretty bad if it did! Safety is important.
My point is that the amperage limit is still valid (at least on my unit).
On my unit:
The wheel and readout goes to a power setting of 12.7.
The amperage maxes out at 3 amps, period. So if you have an atty/carto that draws three amps at a setting of 7, turn the wheel on up to 12 all you want, it's not going to put out anymore than 7 watts.
If you have a 1.25 Ohm atty, you'd be cutting it close, there might be a little room left at the top of the wheel. (3amps, 1.25 Ohms, 3.75volts, 11.25watts) So 11.25 watts is the power limit, even if you turn the wheel on up to 12.7.
With the 1.25 Ohm carto: The Vari would give an error message or shut down in that 3.75 volt range. You'd go into the menu and kick the voltage down a notch or two to get it working again.
With the 1.25 Ohm carto: The Darwin would just stop adding voltage at 11.25 watts, even though you can still crank the wheel up to 12.7.
That's the 'big' difference when it comes to how the two devices deal with the current limit. No brainer with the Darwin. You'd want to be 'aware' with the Vari.
Darwin = Overpowered luxury model with automatic everything.
vs
Vari = the sporty model with just the right amount of power and full manual control.
Both fully loaded with safety features, just a different approach.