I think I'd like to see injury with diminished capacity and no health packs in a "realism" mod.
I remember only one game that I've played that REALLY did that. Discounting games like SWAT 4, OFP/ArmA or R6 where I've had a leg hit slow me down/make me crawl or an arm hit screw up my aiming, and that was Heretic II. An old Quake 2-engined game that was fairly arcade in MP with one exception--when fighting with bladed staffs you could on occasion manage to sever another guy's arm. If it was his left, he could still attack you but with less strength (one-handed staff doesn't work well), while if it was his right you'd literally disarmed him.
Either way, he'd start bleeding out and would die within about 20 seconds.
Compare that to say the Jedi Knight series where a Stormtrooper dies after you knock off his hand.
The Jedi Master