OK, count me as the third....
I tend to use a lot of Kontakt instances in my projects. Before Logic 9 and Snow Leopard I'd usually hit the 4GB limit with 6 to 8 Kontakts and ended up either bouncing a lot of inst. tracks - or worse, simply crashing. But now things are very different.
Now it could be mainly thanks to the recent Kontakt 3.5 update (4 gig barrier-breaker) that I'm getting a more rapid workflow (18 instances last project!). But something I have really noticed more in L9's favour is how I can leave a project un-played for hours overnight... and next day it's all still working fine. Previously, I'd get a "disk too slow" message, everything suddenly stopping when there's too much in the buffer... but I haven't seen that happen whatsoever lately.
The only slight setback I've had so far was on a recalled L9 project, which had all the crossfades on 8 vocal tracks badly messed up (digital glitches on the fades). I had closed project "A", opened project "B", and then went back to "A" again when it happened. Guessing it was a buffer issue, and thanks to the new track import feature, I brought each track into an empty project and everything was instantly back to normal again. No glitches. Bounced in place, then put the new audio bounces back in project "A".
As a conclusion I'm very happy, and feel this is the most solid version of Logic so far - but that's just my opinion, based upon my own individual workflow... others such as those that rely more heavily on the audio side of things may disagree.