As a stand alone rack I've been using Reason and VStack together to form a nice combo of Reason sounds with VST plugins.
I use a PowerBook G4 (1GHZ-1GRam) with an MBox and a Midiman midi /USB cable connected to a Roland A90 keyboard.
There is a latency problem. I've done the suggested buffer and sample re allocation with and its still bad.
Any suggestions?
Other than the slight latency this set uo works and sounds great.