My group does have rotating SGs, however it is not manditory.
Usualy they fall into the background and are played more as NPCs or left in the lab. Our SGs often play Grogs so they can be a part of the action.
Only people who want to run storys do, we have an alph (myself) and when someone has a story idea they run the skeliton of it by me or ask for a part of the world to call their own. Regios are great for this so a SG can have a self contained world to play with. We usualy start new SGs with regios.
Same here. I'm Alpha and do most - and I don't have any characters myself. And when we play it is almost given in advance what character people will play - and very often only a part of those will play their magus, the others playing companion or grog. We don't do the downtime in-session, so there's little need for pausing over all characters every time + most storys span several session but not several seasons.
We use a 3 story guide system for a group of 12 players.
unfortunately, the group is geographically separated (chicago, phoenix, san jose). So the covenant has various a gold, blue and red team each with a separate story guide. Within each team there is an alpha and beta story guide. Fortunately, the 3 alpha guides and all the players really have some good idea on the types of stories they want to tell.
We have periodic team face to face games, online interteam interaction and rare visiting team games.
While the Nurockrah Saga was going strong, we had 2 people who storyguided; Myself, and Mr. Tuura. However, most of the players have also run a story as well.
Having multiples allow the main SG to take a break for a while. In reality, some degree of collaboration needs to be done between all three, lest storylines get crossed, and someone's feet get steeped on by size 14 hobnail boots...
We had the benefit of being able to run 2 or three stories concurrently, so if a character wasn't studying/doing lab work/recovering from the previous adventure, they were along for the ride.
I've run games where we've rotated a lot, not much though. At best I was still running 75% of the games with other people picking up here and there. In the saga where this was most successful people picked bit of the game to call their own-- one did a storyline about diabolists, another about old gods, that sort of thing. As the Alpha SG I would insist on talking to the other SGs about their plans, enough to have a sense of what effect on the saga it would have, what on going elements would be introduced. Sometimes this didn't work out as well as I'd hoped (one player refused to reveal anything so that I'd be surprised like everyone else-- I really regret that decision).
The other thing I encouraged was for the other SG's to plan what characters the adventure would be for, and we'd share that ahead of time so we'd know which magi, which companions and grogs would be appropriate. It was assumed that no one would run an adventure that would intrest either of his characters, so they'd stay at home. (Which mean, for instance, that the guy who loved fairies and was playing a Merenita wouldn't also run fairy storylines.)
IMS we have an ASG (myself) and the other players take it in turns to act as BSG. Only one person runs at a time but we swap who this is on an ad-hoc basis. While i tend to run the mammoth plot threads, the others tend to run shorter stories. However this is more a reflection on GMing experience (of which i have years and they've only recently started). I also tend to act as rules lawyer for the BSGs and maintain the "fiddly bits" behind the scenes (i.e. how much vis the covenant has, how much loot, diaries of what the mages have bene up to, etc).
This system works quite nicely as we all run things a bit differently, one of my players runs mostly published stuff, one runs heavily adatped stuff and i tend to create the aforementioned epic plot threads. Its nice to vary the style and length of stories.
We all have multiple characters. We tend to only play grogs as NPCs run by the SG, each character has two mages (three in my case sinvce i also run my senior mage's apprentice as a main character) and we run these characters as NPCs when SGing. We don't have many companions at all but these are usually played as sub-PCs or NPCs, we prefer to maintain the focus on the magi.
We haven't really encountered any problems running our characters as NPCs when SGing. If I am SGing i tend to have my senior mage lock himself in his lab and send his apprentice to do the legwork, this way the other players get to play their senior magi without my senior mage stealing any of their thunder (while the apprentice cowers in the corner hiding from the dragons, fireballs and giant bears that tend to make regular appearances in our games).
We've found that having a major NPC (i.e. your usual PC) in the troupe while SGing allows you an excellent means to prod and poke the party into certain courses of action in a nice and natural feeling way. Plot hooks rather than plot hammers.
My groupe has four players, and every player is a SG. Each has its own domain (infernal, dominion &mundane, magic, faery). I do the magic and convenant. This works quit well, though we run a lot of stories at the same time. We profit very much from our wiki-site so you can keep up all the information.
I use multiple storyguides whrn I can. Sadly of all of the Ars games that I've been involved with over the years only one really had multiple SG's. The rest of the time it was only me.
Typically the storyguide's characters aren't involved in the adventure that they run.
With a rotating storyguide it's been my experience that the storyguide goes to the people who are willing and prepaired. Most folks understand that it is their obligation to shoulder a bit of the SG work in order to reap the benefits of being able to play.