We tried private matches with Gears 2 but it lasted like a week because all anyone did was complain about wanting to play against randoms when the online didn't work, so everyone eventually buggered off back to CoD4 and Krono, Miss K and me went back to Halo 3.
It might be different this time because the desire to play randoms is not there because levelling up is no longer an issue in private games. Only trouble is p2p.