I think they should go with H2/3 style. Members here argue that Reach gives you more survivability but I would have to disagree. In reach, if you have been damaged in a fight that your now at 1-shot (and survive the fight), if you dont find a health pack you will always be 1 body shot away from death after your shields are down. In H2/3, if you take the same amount of damage that you are now a 1 body shot kill and survive (Note H2/3 still has health, its just hidden), your health regenerates with your shields and no longer a 1 body shot kill after re-losing your shields. So really, the most survivable system is the H2/3 way because you never need to find a health pack.
However, I would like to see my health bar, so that I can tell how close I am from dying from AR or BR body shots. Just keep it in recharging form.