My group is fairly new to DFRPG, we decided a few months back to give it a try because we had all read the books but we had zero FATE/FUDGE experience.  We decided to do rotating DM (I was first), with short episodic scenarios.  Since we only play short sessions, just a few hours a week, we typically shoot for rotation about once 4-6 weeks.  I think I had the longest GM stint at 7 sessions because I had prepped something too large, next GM had 5 for this scenario, and current one is in week 4 and looks poised to wrap up in one more.  It's worked fine for us so far.  There's no overarching plot, though we do feel free to share NPCs as needed.  When asked by the current GM I've roleplayed some of the NPCs from my adventure that the party wanted to get in contact with to solicit information or help, for example.  Sharing NPCs keeps it from feeling disjointed. 

The big advantage of rotating GM duties is that the scenarios seem more polished.  Since everyone gets an 8 to 10 week break between GM session then there's plenty of time to put together a very solid adventure without feeling like you have to crunch to stay ahead of the players.  I'm due up in the rotation again soon and I've already got the villain and some of the scenes I want to spring on the players worked out.  Having them early means extra time to ponder and tune them.

One last warning, the other thing to watch for with rotating DM is fluctuating party makeup.  This has been something of an issue for our group since we each retire our PC temporarily when GMing.  Hence the party makeup fluctuates a lot.  I have the only wizard or even spellcaster of any sort in the party and thus when I'm the GM the party is very light on magic and has to do things the mundane way mostly.  Conversely when the player of our best stealth/burglary/investigation character is GM the party becomes very light on subtlety.  When the guy with the mega strong werebull is GM, our party loses most of it's teeth (well horns) when it comes to brawling.  Each GM has to account for that in adventure planning. 

This is just one more reason I do not like, nor use social combat.

It seems like DFRPG wouldn't play right without social combat.  One of the key things that keeps my players from making physical combat oriented minmax munchkin characters is the knowledge that such characters would suck in a social conflict.   

Plus of course, social combat is sweet.  Sure encountering an ogre in the nevernever and killing it is cool and all.  Even cooler is to pull your weapons, give him a few hard looks, suggest that he had better keep walking if he wants to keep all his limbs, and win without a shot being fired.  I was part of a party that pulled that off and it was wickedly awesome.