Have you ever co-GMed? Would you consider it? What are the pros and cons?
I have actually co-GMed, though it's been quite a tick since I've done so. Way back when I was still at Wittenberg, a good friend and I co-GMed an end-of-year one-shot which actually ran over two days in length! That session, one of the infamous Blackfall games from which I took my company's name, was an absolute tour-de-force in terms of challenge. Players rose up, characters fell, and the illithid conquerers of Blackfall were ultimately undone by the acts of a single dwarven mage who sacrificed himself to shunt the city into a different timestream, removing it from the world at large.
Co-GMing, as you might imagine, comes with a good deal of baggage. While as a normal GM, you might enjoy relative autonomy in terms of the plot, overarching story, and presentation of NPCs, these become areas of consensus when someone else is riding shotgun in the GM's chair. However, that same consensus can also result in great ideas that may not come from one GM alone. And what, if anything, are RPGs if not some sort of collaborative storytelling?!
|Is there room back here for two people?|
One potential solution that I've seen to this dilemma is to simply alternate GMs--either the GMs share one character or play their own while the other GMs, with the GM's own PC fading into the background for that individual session. While I haven't actually attempted this concept yet, it's been raised at our Friday night table as a potential alternative for some of our busier players, who may not have time to prep for a full session each week.
Overally, though, the biggest key has to be communication. If you're going to co-GM, pick someone with gaming preferences similar to your own, such that the disconnect of switching GMs doesn't throw off your players. And, throughout the entire process--from prep to play to prep again--you've got to keep talking and making sure that all the GMs are on the same page. Do that, and this crazy idea just might have a chance.