I agree with Kepler. As I pointed out in my FVS2 review a couple of days ago; the S2 w/ the 3.7 batteries runs very hot IMO. Although my technique is very conservative, I find that quite often I either combust or am on the verge of combustion. I too find the vapor to be harsh, hot and almost smoke like. Though i must admit , the FVS2 does medicate the shit out of me..LOL.
As I mentioned in my review last week, I used the following technique: Hold button down for 4 seconds, slowly inhale for another 4 seconds, release button and finish my draw. Hardly an aggressive technique IMO. Nevertheless , I combusted twice.
That's why I think Pak is on to something when he says that there must be considerable performance differences between the various units. After all, prior to me purchasing the FVS2, Pak was saying that he felt that combustion wasn't really an issue anymore with the S2 spacer. In fact, he said that he even held the button down for 12 seconds w/o inhaling and didn't see any evidence of combustion. It just seems strange that Kepler, myself and several others are having a much different experience than Pak and some of the other early testers....