Update. So far it all works ok. I followed Rachael's advice and haven't pushed the button yet. The cpu usage meter is quite fascinating. It seems mine varies around low 40's to high 50's when playing a BB file of all realtracks with bpm at 104 and tracks that are native 120.

The odd thing is running Realband when I click on "select and generate real tracks" and the list comes up the cpu meter maxes out - but I believe this has been going on before the upgrade even tho I wasn't watching the cpu meter then.