I've yet to find a game where waiting for my health to regen hampered me in any way. In Vegas 2, was pretty common to run out, get a burst of fire and almost die, cover and heal, while I killed the foe. Regenerating health does work in the DX setting, augmented human and all. When you're just some schmuck special forces guy, eh not so much.
In any event, Eidos claims (heh, right) that the health regen in the game will take a good bit of time to kick in.