I too have been following this thread for months! When 10.8 came out and I heard it had ironed out some kinks from 10.7 I decided why not update my seemingly old 10.6.8 to ML and take advantage of the "performance advances I'd seen from SL/L comparisons on YouTube. BAD DECISION!!! And I knew better too than to jump from a stable platform to a new bug ridden piece of garbage disguised as ML that I grew to hate after maybe 1 full, or should I say "wasted" day trying to compromise with the lag. 10.8.2 was what I'd upgraded to, and the following day, started the degrade process back to SL, which with all the system writing/re-writing On a brand new SSD I'd saved specifically for a fresh install of ML, left me all but wishing we as users could collectively fire whoever pushed 10.8.2 out to the public. Ahh
Ranting aside I did like the features in ML, the subtle refinements I desired and have been waiting for Apple to put out 10.8.3. Seriously I was checking everyday for the update and the 160+ days it took. It came out and with 90% positive reviews (or was it the 90% lack of frustrated raving.) decided to try it again.
After a fresh install, combo update, time machine migration, and onyx, Logic 9.1.8 and ML 10.8 are a go for me.
I do notice the minor lag as described above, but it is nothing compared to the previous experience. And even SL had some weird issue in regards to, "Disk Too Slow" or the even more frustrating "Need to Unpack Folders" (when I didn't even have any. Pause/play was faster with SL but I'm definitely content now. I even think the processor performance is a tad better in ML when it comes to handling all the plugins! Loved 10.6.8, Hated 10.8.2, and growing to be just as fond of 10.8.3.
Now Apple could you keep the up the momentum and do just a "minor" update to ML, Logic, whatever it needs to make it as snappy as 9.1.8 was on 10.6.8? Then everything would be perfect in the apple world... At least in the Audio Production side of the apple world...
Oh and be able to set user choice of sample rate. I'm always having to manually change it to 48k... Sorry gettin off the focus there. I don't want to overwhelm your best programmers with too much to handle! Lol