I have an IPV D2, Snow Wolf 200 LE and the Istick 100W. All have their plus and minuses. My wife uses the D2 with a dripper and has no issues, runs it at 70 watts most of the time and battery life is ok. I use the sw200 the most, has 200 watts, although it does pulse above 150 watts, does tc with ni200 just fine, but its a little wonky with ti, probably because the mod is not programmed for it. The Istick 100w is more of a back up device and does a nice job for what it is. I am going to be getting the IPV3 LI soon just to have another device to use and learn more about vaping and tc. The IPV 4/s has no interest to me, I think the IPV3 LI usurps it.