I must say a five player co-op Gears of War would be some sweet action. I still love Gears of war 1,2 because It is too adventures Game. I am sure that Gears of war also would be great.
I played and enjoyed the first Gears Of War coop with a mate on PC, but after finishing it kinda just uninstalled it and forgot about it; if i can get my hands on a 360 before release i will do the same with this one. (Without the uninstalling stuff of course)