a very annoying problem, yes.
the workaround with terminal mount seems to work, indeed.....i had a crash after mounting the mag again with fw800 after the esata test, but well......
to sum it up:
sudo mkdir /Volumes/red
sudo mount -t msdos /dev/disk6s1 /Volumes/red/
sudo umount /Volumes/red/
"red" is the name of the mountpoint you set.
"disk6s1" the identifier in disk utility.
after line 2 it should mount and later you unmount it....
it''s kinda ok to hack that in in order to safe 5-8 mins copying time.
But lets hope for a driver update from sonnet.