Oh, and the maps are really the only problem, the players and guns, vehicles etc could all be scaled down pretty easy, but im not sure if a mutator could do it, i tried making something like that for 2k3 and it worked good but you couldnt crouch in the midget or giant state.... But just redownlaoded the players and stuff rescaled wont be that bad, and will allow to play in the ut gametypes, which imo would rock, cause i hate gay ass weapon pickups and the abaility to carry all the guns that ut has... Classes would make ut 100% cooler.
The biggest problem will be custom maps, not only will people make them and then find out they are too small, some people will want to make a XMP map then also use it for ONS which prolly wont work now.... And if its that easy for the mapper to just rescale then the xmp team needs to do it before release to match ut scale.