I just upgraded my slave MacPro to SL so that I could run Omnisphere and Vienna Instruments in the Vienna Ensemble Pro server in 64 bit. The upgrade was seamless and everything is working as it should. The slave computer is essentially working as a sound module so it was an easy upgrade. SL is so snappy. Even the colors are sharper. It feels likes the machine has had a processor upgrade. I'm impressed with that. Considering the limited function of this computer in my setup, this has worked out really well.