I have had good luck with them, myself. There was a recent thread though where various people said they always failed, which is not my experience, but was a little disconcerting. I actually carry a bit of both, but I normally reach for the PSA ones, and none of mine have failed.

It has also been my odd experience that one can drive through terrible junk for a 1000K, no problem, then I get several flats in one day, often not in a place where there are any noticeable problems, or because one just didn't clean up after the first flat.