I have not got any crashes, but I also experience some crackling.
I am running a 2.6GHz i7 (quad) with Win 7 (64) and Reaper (32) and 128 byte buffer.
My project contains 2 instances of CS-80V (old version), WOK Cromina, Taurus and Ambience Reverb plus now a Stage73. Without the Stage, everything is very smooth. As soon as I add the Stage73 to the project, I get crackles when playing the Stage73. This is independent on whether the GUI is open or not.