I think that NXE has nothing to do with the loading times (I might be wrong), but there is a huge difference in running the game from the DVD and HDD. It loads much faster from HDD.
Yeah I'm up for it too, I have already completed some of the maps with my mate, but it's more fun to play with a full team. MSG me or send me an invite whoever wants to play a mature coop campaign on Xbox Live.
My gamertag: shadowfacex