I've been fighting the need more moderators battle for a long time, especially as social proliferation and saturation gets worse .. as much as I love G+C, it's going to add more logs to the fire .. I do think +Amy Vernon
idea of asking top contributors is best bet. At #smchat
on Twitter (future G+C) we spread the load by asking each moderator to cover a portion .. very much like a journal/paper .. features editor, sports editor, etc. Basically, creates focus and divvies up the work ..