I have used QF, bought from the Spectrum Labs website, and it worked perfectly for me.
Killer had everything right on. My only comments would be to make sure that the QF you buy is unopened (still has the plastic wrap on it) and a new version. You won't be able to check the version at a head shop since that information is located inside the package, but if you buy online it should tell you the batch. The one I used was QF5.7, Batch F11F-09.
(From everything I've heard they go by the heat strip on the cup, they do not manually test the temperature).
Heating it up is the hardest part, and it's really not hard. I heated mine up two times before I left, each time 10 secs (didn't get hot enough first time), wrapped the hand warmer around it and crotched it (I'm a girl) for approx. 25-30 minutes - no problem. If for some reason your temp drops, use the hand warmer provided to heat up the temperature strip on the cup.
QF really saved me and I can't say enough great things about it.
I have no doubt you'll pass and I wish you all the luck, even though you won't need it. :thumbsup::hippy: