It's hard to visually see a performance increase, but when I loaded up a large bank of samples rewired Reason and messed around for a while it seemed to be more responsive, smoother and snapier.
This should only have a significant impact on your
experience with Live under circumstances when
streaming many tracks from disk would have limited
your performance. On my desktop machine, I
can more or less double the number of stereo tracks
I can play back (to upwards of 40) this way.