Excellent protection, suprisingly good airflow (open top), unique look, good fit, great for reffing
Protects too good for game play (can't feel hits), can get warm on shoulders
I bought my Predlocks with the intention of using it for reffing the PSP and local events and for using it for fall "Zombie" games that only count headshots. I used it at Chicago Open in 2009 when it was rediculously hot, and didnt' ditch it until the afternoon when it was just too much. Invariably when I got off the field and took it off, two or three paintballs would fall out and evidence of other breaks would show, hits I'd never even felt. In fact, I decided that I couldn't wear it in a game because I was afraid I would get shot in the head and not know it, and I don't want to play like that. I used my Predlocks for reffing local events and always get compliments on it (almost always positive, which is incredible in the tourney world where half the players have insecurity issues). Just take them in the shower with you to clean them, too. I never had any fogging issues because of them, and they fit really well. The guy who makes these is a PSP ref, so he isn't that hard to find. Or google him.
For reffing, I really recommend this if you don't like headshots. I don't recommend if for game play because it works too good, and you might inadverdantly play on. If it came with built in A/C, I'd give it a 10 (though it holds cold water pretty well).