hey keefer, the I'm working in about a 55 degree work environment, I use the fast and usually have a lamp overhead that heats the surface to about 65. With the epoxy not preheated, and using fast, I get a pot-life (in the 55 degree air temp) or about 45 minutes at least, I havent gone past that yet. I also have had almost no blush, and in some cases none, because it's cold and the curing process is slow, even with the heat lamp (only truly heats the surface).
Blush is no big deal, just takes a scotchbrite and some water with 30 seconds of scrubbing...