I laughed at the ridiculous claim in that thread that the tires slide out because the sidewalls were too slick. In order to ride on the sidewalls, you would have to lean so far that the handlebars would be practically be scraping the ground. With a fixed gear, you would obviously pedal strike first...maybe that was the guys problem.
At any rate, I've gone through several pairs of folding gatorskins on my commuter fixed gear and have had no problems with them or dry or wet pavement. Very very few flats and the tires hold together well. A good kevlar beaded tire will not slip off the rim. Gatorskins are considered to be training tires. They don't perform at the level of a racing tire, but will last a lot longer and still are more than adequate for everyday applications.