Paul,
> Has anyone experienced real performance gains by moving the pg_xlog
> files?
Yes. Both for data load and on OLTP workloads, this increased write
performance by as much as 15%. However, you need to configure the xlog
drive correctly, you can't just move it to a new disk. Make sure the
other disk is dedicated exclusively to the xlog, set it forcedirectio, and
increase your checkpoint_segments to something like 128.
--
--Josh
Josh Berkus
Aglio Database Solutions
San Francisco