Don't forget that while there is airsoft games that use LARP elements, there is also LARPs that use airsoft.
I organized and I play in such games (Cyberpunk and Post-Apocalyptic). Because most of our players come from more traditional LARP games, it's very similar to those, with the exception that airsoft guns are used (and the setting, of course). We try to keep it that way, because most players prefer roleplaying instead of combat. Airsoft is primarly a tool to represent more accuratly firearms: Nerfs guns have poor range and accuracy, lasers are lame, rock-paper-scissors is to slow and breaks the roleplaying.
Our rule for combat is very simple. Every attack deals the same "damage". When you're it on a limb, you lose it; when you're it two times on the chest, you're down. Armors protects you from a certain number of attacks. Most of the times, the combat are very fluid.
I think both airsoft and LARP can gain from being mixed together. Airsoft has certainly given us the opportunity to do realistic battles and having a kick-ass visual.