There was a post on the forum that other day where someone used ohm's law to figure the magic number was 2.2 ohms for the twists to achieve maximum performance without hitting the amp limit.
I think that was me. And, yeah 2.2ohm came out as having the most range available for stuff I could find easily. If you really wanted to figure it out, you can solve a set of equations
but I just don't care that much.
A 1.5 Ohm anything (single/dual/eighteen-coil whatever) will hit its limit pretty low on a Twist. If I'm doing the math right, it tops out at about 6.6 W. The same thing on a normal purely mechanical mod without a current limit would give 9.12 W (assuming the battery could deliver ~2.6 A
which most of them can but the Twist can't).
Based on the math, I don't think dual coils are really worth it on VV. But I haven't used one. I'll have to try it at some point. But based purely on the math
I'll be waiting until I get a simpler mod with high-drain batteries, because I don't expect it to work well on my Twist.
As to the OP's actual question
Using 1.7 and 2.5 ohm stuff, I do feel/taste/experience a difference b/t settings on my twist. It's night & day compared to a little cig-a-like 901 battery using the same stuff. At some point in the scale, turning it up more doesn't give any noticeable change
and that happens right when it hits the current limit
for a 1.5 Ohm device
that happens at 3.1V.
There's more usable range of powers the higher resistance you go
up to the point when the device can't provide enough voltage to hit its current limit
which is where the ~2.2 Ohm "ideal" came from in the stuff I posted. If you're around there, you get to use the whole range of your twist
which corresponds to having it vary from 4.6 to ~10 W
which is about the same range as the Kick
and it tops out around 4.6V, which spreads that power range out to fill
almost the whole range.
Going too far
using a 2.5 or 3.0 ohm carto/atty would give you the full range, but it also tops out at 7.7W with a 3 ohm atty/carto @ 4.8 V
which is the whole reason people did stacked batteries before these VV devices came out.
I have nothing experimental to back it up, but if you're going to use very low resistance or dual coil stuff
high drain batteries and
very simple mods seem like they'd give better results than any of the cheap variable voltage stuff.