I'm thinking your problem with the iStick is the same one I'm having, and it don't think is has anything to do with the voltage or wattage, I can get it turned down far enough. The problem is, even when dialed down to get equivalent power, the iStick is to me a harsh vape compared to the same toppers (currently Areotanks for me) on the iTaste VV V3. And I think that's because the VV V3's, just like the Provaris, put out a flat waveform: the voltage is what it is, and it stays there as long as you've got the fire button pressed. Ask for more power, it outputs a higher voltage, and keeps it there as long as the button is pressed.
OTOH -- and I know most of you know this, so forgive me if I'm being tedious here -- PWM, pulse-width-modulated devices like the iStick, like the DNA 30's (but not the 20's) put out a constant voltage (their max voltage) which they cycle on and off during the vape. During the on time they're burning the juice with a higher than average voltage, and doing the off time it's not getting vaporized. There's a lot of talk about whether anyone can taste the difference, whether there's so much thermal inertia in the coil/wick/juice/atty/system that for all practical purposes it's a moot point, or whether it really does make a difference.
Many people say they can tell the difference. I was agnostic on the question until I got the iStick, now I'm a believer -- I can tell the difference. I expect how much a difference one would or would not notice, in addition to individual variations in sensitivity, has to do with the details of a particular setup: a mod whose duty cycle varied between the boost voltage of ten volts and zero volts is likely to produce a different vape then one that PWM's between eight volts and zero, for example. Some atty "systems" (by "system" I mean to include the coil, deck, amount of juice close enough to the coil to contribute to thermal inertia and anything adding to or subtracting from the thermal inertia) are almost certainly higher inertia than others, and while they would be slower to heat up and cool down, it makes sense that they'd produce a better vape with a PWM device than an atty with lower thermal inertia.
Bottom line for me now is I'm passing on PWM mods. DNA 30's (not in the cards anyway with the 40 out) and iSticks out. Provaris, DNA 40's, the new Innokin SVD 2.0 in.
A year from now there will be no PWM mods on the market. (Assuming Deeming doesn't get rid of them first. Little hard to see how they can regulate a flashlight with replaceable bulbs that use standard 510 bulb connectors.