I don't do it all the time but I've used it for a lot of things...
One was when we were moving an environment from one location to another 15
miles away.
We had two servers but didn't have two libraries (and we had big diskpools
to hold multiple day's backups)
Anyway, I backed the db up to a disk file, ftp'ed it over to the other
server, restored the db over there, brought up the environment, allowed the
clients to start accessing the server, then had IBM move the ATL.
Worked slick as a whistle !

PS If you are going to back the DB up to disk, I'd make sure the disk were
protected by either Raid-5 or mirrored, then I'd want another TSM server to
back that file up to... (or at least another system to FTP it over to)

Dwight