Yes -there are several threads about Win8 on the RME forums. I knew going in that there could be issues with Firewire, but I thought USB would be ok. It worked, but not at the latency and track counts I use that are very stable in Win7.
Same results regardless of DAW (Sonar X2, StudioOne 2.5, and Cubase 7).
Back to Win7x64 for now.
John