session servers in ram

I'm looking at running session servers in ram.  All the data is
throw-away data, so my plan is to have a copy of the empty db on the
hard drive ready to go, and have a script that just copies it into ram
and starts the db there.  We're currently IO write bound with
fsync=off using a 15k5 seagate SAS drive, so I'm hoping that moving
the db into /dev/shm will help quite a bit here.

Does anybody any real world experience here or any words of sage
advice before I go off and start testing this?