To answer your question, we really need to know at what point in the charge cycle of your battery are you MOST happy, with EACH coil.
basically... fill in the blanks...
On my 0.25 Ohm coil, I'm happiest with a voltage of ________ .
On my 0.80 Ohm coil, I'm happiest with a voltage of ________ .
On my coils between 0.25 and 0.80 Ohms, I'm happiest around ________ volts .
As you have already figured out, all things being equal, your watts are right there. Obviously though, once you start building different types of coils and running them at various volts... using different wicking materials and in different ways... with different juices... well, everything changes a bit. But... if you keep the same atty's with the same type of coils/etc... you can figure out the wattages required for yourself... the last complication is if what you buy is PWM'ing things and how that will effect you.
I like some juices at 7W in a 2.5-3 Ohm bottom coil tank... other juices I absolutely LOVE at 80-120W via RDA using Rayon and exotic coils... and THIS is the BEST reason I have had to buy variable wattage devices and not only that, but also to have various RDA's... tanks... and battery/mods around.
