Aren't these games all P2P? Dont think server has much to do with it other than a server lobby and doing those connections; once in game lobby its all player-based? From all tests I did anyways (hey i could be wrong)... I kinda concluded hit detection was host based for everything (one exception). If it landed on the host's end, it landed. Just like Gears of War 1.
Story time mode:
One time I was on skype and playing with a buddy, I was axel, he was Meat Wagon.
I was charging towards him with my special on for a crush. On my end, he jumped over my car, and i hit thin air. Yet somehow the game gave me the crush points, counted it, and he died.
On HIS END as well, he jumped my special, and still died.
Neither of us were host... so the only logical conclusion to me was Host has a bit of an advantage... but they chose to offset this advantage by making the host's ps3 crash and freeze a lot! (kidding, but cmon!)
Mort's video kind of solidifed that notion:
http://www.youtube.com/watch?v=ChMnNNGStiYOn Mort's end he clearly avoided the health semi. On the host's end, Mort's car continued for an extra second BEFORE turning. And thus host's ps3 witnessed Mort take the hit and then swerve to the side injured. Host's PS3 told Mort's PS3 that he was injured, and docked him the health.
It does suck though with laggy hosts and long distances. The rams really wont connect half the time. IMO they should have made an exception and changed the hit detection for rams to client-side. It would make your big dogs better heh (with their already current dmg/health), but ramming wouldn't be fruitless at times.
Many people complained about folks mysteriously getting health but that was an easy one. The only exception to "the host sees the true game" is the health peds. Peds are completely desynced from ps3 to ps3 so someone might seem to grab health from thin air. (it was identical in TM2PC).
I think they shouldve used a Halo approach, where there is no true host advantage. It should be, if a weapon hits you on your own end, it hit. That way if you avoided shit, you avoided it.
I once thought they maybe made everything so damn unavoidable/undodgeable and spammable to simply alleviate player frustration in instances where they think they landed a weapon (on their own end, and it appears that it does) BUT in actuality the other player dodged it on their end and it missed. It also helped mask this terrible hit detection choice. Gotta have dat dodging and driving, or imo its mostly just attrition wars. But I have had a lot of theories on that can of worms, jury is still out