Ok.. 1st and foremost, yes, you can absolutely tootle puff using a TC mod, and it's not hot or harsh or anything like that -- normally I'm tootling around 8-9 watts, which ain't exactly setting anything on fire.
As far as nickel, I can't really say yay or nay, because I went the titanium route; I suspect I'm sensitive to nickel.
The sub-ohm coil is ONLY because of the properties of nickel or titanium; it does not make the thing a "cloud machine" -- it's heat that generates clouds, and since it's a TC mod, you can set any temp you like -- mine is set at anything between 370F-390F -- no idea how that converts to C, but it's on the low end, not really hot at all -- most of those who like hotter or cloudier vapes are somewhere between 400F-500F.
What is the mAh rating of the iStick TC 40w? Because I got the Evic-VT which is 60w, 5000mAh, and it runs down much faster than my 2200mAh 30w iSticks, or my 2000mAh 40w Coolfire4 -- I suspect that's because it's sensing watts, temp, and resistance all at once, real time -- you can watch all 3 of them fluctuating as you take a hit -- and apparently all that real-time monitoring takes a real toll on the battery. Also I would say that 40w is probably enough; I have mine set to 35w, but the only function of the wattage in TC mode is to bring the coil quickly up to the set temp -- once it's at that temp, the TC kicks in so it doesn't go higher, and the watts drop -- hence all the real-time monitoring that really sucks the battery. But if you like it any warmer than about 400F 9whatever that is in C), then 40w might not be quite enough.
I'm kind of a tightwad, so I wouldn't have gone with a super-expensive mod -- fortunately the Evic-VT, in the express kit, is only $49.99, at
VapeNW -- and that includes a charge cable AND a silicone cover for the mod. If you already have a 1amp wall wart, you don't need to buy the full kit; you can use any rebuildable atty on it, and just use nickel or titanium wire to coil it. It does have to be below 1ohm to work in TC mode, and lower is better, because apparently the resistance climbs as it gets hot, and if it goes over 1 ohm, it will drop out of TC mode. (the Evic-VT is smaller than it looks in pics, but it's also rather heavy -- much heavier than the CF4 for instance).
Andria