First, a caveat... when we first upgraded to FMS11, we changed a few other things at the same time, so our experiences could be unrelated to FMS11.
Everything seemed to work fine when we were testing, however once we got a decent number of FM 8 users connected (around 100), we started having weird issues. We eventually had to roll back to FMS10 and revert to a backup database.
We then upgraded all clients to FM11 first, waited a couple days, and then upgraded to FMS11 (without making any other changes), and for the most part it is working ok.
Thanks Matt. This is a 12-user installation so hopefully they'll be OK. Plan to upgrade at end of August to FM11 client software. Their budget is VERY limited right now. Appreciate your sharing your experience!