For me the problem with high health is that you can get yourself into a good position and completely get the jump on a group of - say - three people (and I don't mean camping, I mean flanking and coming up behind them) and, short of them being full on incompetent, there's really no way you can actually kill all three. A couple of bullets in their back should kill them. Having to plug one person for so long that the other two can turn around and combine fire on you just turns it into a numbers game.