We just started rotating GMs after years of not doing that, and so for it seems to be working. As has been pointed out in this thead, it takes both maturity and trust for it to work. If one of the GMs is going to cheat in any manner, it's just not going to work. More, if one of the players even thinks one of the GMs will cheat, it's not going to work.
Some of my players suggested it after the campaign had already started. They believed it would help me with GM burnout, since I run two games per week. The npc runner became my pc, also their suggestion. I was a bit leery about the idea, but I do like the opportunity to be a player. I love GMing, but sometimes it is fun to have few responsibilities and just roleplay and fight.
We give eveyone karma evey session their character is on a run. As long as GMs aren't cheating to make sure their character doesn't get shot at or whatever, it's fair and everyone's karma stays the same. In fact a couple years ago I removed ALL individual karma rewards, after some incidents with player jealousy. Any bonuses go to the team karma reward, and not just in the rotating GM game.
One problem I can see is with my overall campaign arc and ongoing storylines and npcs. I'm not sure yet if the GMs are going to want to take part in running this. The problem is that if they do I have to fill them in on campaign secets, such as who the corrupt cop ring that harassed them is working for. I know they won't cheat, but the game will be less fun for them as playes if they know these things, like reading ahead in a detective novel and knowing who did it. I don't think they'll want to take part though, which will solve the problem. Most of our GMs just create shadowuns, no long arcs or ongoing storylines.
NPCs are another problem. I plan to just ask them to talk to me before using any of them so that I can tell them how to play them. Hopefully they can create their own though and only use my fixer npcs.
I am a bit worried as one GM who hasn't entered the rotation has stated the danger level is too low and plans to set it higher when he runs it. Also he always uses published adventures, which I'm also a bit leery of. I purposely set the danger levels for this campaign fairly low, both so that we would have a long campaign and have time to enjoy the characters, and also because for a year or so I became known as something of a killer GM and even tpked a party at one point.
So far it's been enjoyable though and I just GMed my last session, so I'm looking forward to having 3 full weeks to read SR books and work on my adventures and camaign design. I have to admit trying to run two games every week stretched me to my limits.