5 players, 5 potential DM's.
Everyone wanted to DM, but we decided upon several things: 1) Only 2 of us were really any good (not really a group consensus, but I've only had fun in one other campaign and... I'm arrogant sometimes

), 2) Several of the potential DM's run games that start strong, but then die REALLY quickly, this leads to lots of old character sheets (my Half-Orc Fighter, Rivvell will never be played...

), and lastly 3) With so many DM's, the campaigns will never get anywhere.
That last one was the clincher. We decided to cut down to an average of 2 DM's. Every once in a while (when the defaults are feeling burned out or in non-DM mode), someone else could run for a night or two. Since the others tend to run veritable one-shots anyways, this doesn't pose much of a problem.
As of right now, the Eberron game is running fairly smoothly and every once in a while, I coerce the other DM into running his campaign (which I very much enjoy!). He always seems apprehensive, but he does such a good job...