Two things. If you do not utilize a DAC that requires integer mode to sound its best, i dont believe the OS is materially different performance wise. Some have claimed that Lion sounds better....i cant hear a difference but they are in different systems. The older Mac mini though isolates its USB ports whereas the new one does not, they are shared ports. Again, picking nits here. I have both an older mini in my main rig and a new mini running Lion in my office. They both work great with Pure Music, just no integer mode with Lion.