I don't really care how they represent it, I just hope it automatically regenerates durring multiplayer. Seriously, picking up health is arcade like and a thing of the past. Of course I understand they may keep the non regnerating health system for single player since it's been that way in every gta, but I really wouldn't be opposed to seeing it done away with all together.
With that being said, if there is regenerating health, I think the screen should go red/blurry when close to death (perhaps accompionied by a health/damage bar like max payne 3) and after a period of time safe from damage it begins regenerating.
With regenerating health we're able to have a more realistic and less frustrating experience. Think of gta 4, you could get sprayed with bullets (and even take multiple bullets to the head) and come out of it with just enough health to eat a hotdog. In red dead and max payne, however, bullets did more realistic amounts of damage and head shots were 1 hit kill on the player. This made the game alot more fun and believeable, and unfortunatly with non regenerating health (and without multiple health packs throughout missions and without lots of cover hugging) games can be frustrating at times and kind of remove some of the fun element in my opinion.