I usually play during U.S. prime time, but I logged into the main (Pizza) this morning for a few quick sorties.  Uggh.   Man, is that map empty with < 150 players.  I think that there should be a check so that when the number of players drops below a certain threshold (e.g., 250) for a certain period of time (e.g., 30 mins.), the big maps get swapped out for the smaller ones.