I have done that on various levels.
My current campaign we have a primary GM, but as the GM is working on the next major leg of the campaign, real life comes up, or other issues, we have two other GMs that stand in, basically doing really short legs or one shots. I do like this, but at the same time it leads to your character being out for a few runs. The way we handle it is that we still award the money/karma to the down players for that week (although I am going to recommend it going at a slightly reduced rate in the future).
Pros: Its fun, it keeps from GM burnout, you get a variety of story telling.
Cons: There isn't a whole lot of continuity between campaign missions. There has also been some internal conflict that has arisen. There needs to be more overlap in roles, GMs may have different ideas on how the campaign is runing
My 3rd Edition campaign was my favorite though. It was similar, but we had two primary GMs. We each had complete control over our aspects of our missions, but we did end up having an overall story that the GMs agreed and co-wrote beforehand. We did implement a reduced GM's character karma/nuyen reward (I think we took a 20% cut on both during our downtime, and loot sold wasn't split to them necessarily). This did put the two GM characters a little behind, but ShadowRun is developed to a way where you can have a difference in power levels on characters and still get through. And the team also had a community pool for everyone to use, and the GMs tended to mooch a little bit more off of that than the others but nobody really had an issue with it.
Pros Its fun, lowers GM burnout, linked overall story arcs, GMs were on equal ground on decisions
Cons: GMs still get a little behind, still somewhat low drama
I would suggest the 2nd way, if possible. It is definitely viable for some groups, but not for others.
In ShadowRun, there are some decent excuses for being out for a few weeks for your character. For example, I used my character's time away to be completely rewired and training (upgraded or replaced a lot of my ware, did some extensive training etc). And the next GM allowed my character to bypass most of the availability rolls since it would have easily been done in that time.