Open Tables VS Set Groups

Hey all,

I was hoping to get some feedback from GMs who have run open table games (West Marches style games where there are many players in the group but only a few join any given session) as well as set groups (standard, every player in the game tries to make every session) on SPG and what the good and bad of each in their experience was.

I've only GM'ed for set groups in the past but I think open tables seem like a better fit for SPG and online roleplaying and so I'm trying to get some more research into them before I start setting up my own games.

I appreciate any insights you might have or any links to helpful articles you might have come across. Thanks in advance!