The slides are primarily just for aging the phosphors evenly so you can get it calibrated after 100 hours or so and it will be stable.
As far as helping with IR, the only thing they do is help blow through the first 100 or so hours faster, and panels are more prone to IR early on. But the set isn't any more resistant to IR after 100 hours of slides than it would be after 100 hours of viewing regular full screen content as I understand it.
I've had the 55" Panny UT50 for two weeks now. I've not seen a hint of IR on it. I've not done any gaming marathons or anything. Longest gaming session was 3 hours or so, and have watched channels with tickers etc. for 3-4 hour stretches. Didn't even notice any IR when running slides the first week. Now I don't bother actively looking for it really, but haven't seen any hints of it after gaming or changing channels etc. But obviously I can't speak to how it would do with a longer gaming session or being left on ESPN all day etc.