Turned on all the display quality settings, including GPU acceleration. Played the animation and it was smooth. No visual anomalies or such. Things worked quickly, I was able to scrub the timeline and the display kept up with it; for both ASP native drawings and imported bitmaps. I have a dual display and ASP kept the position of the palettes on the secondary monitor across restarts of the app. (I have the Actions and the library on the secondary monitor).
It may be just me, but the app seems to be … ahh… snappier than v 9.5. It just feels faster and more responsive.
Preview animation worked just like in the various demos/tutorial videos. It ran through the timeline once and then popped open in my MP4 viewer (VLC, fwiw) and played there. All good there.
Opened up a few of the default examples (the monster, the flytrap plant and the cat (?) man) files and rendered them out. They rendered out quickly. I did notice that it seems like a few Quicktime export options were missing ( like the Animation QT setting), but as I usually export as PNGs and then process it out from there, that wasn't a show-stopper. And the various H.264 settings are just fine for posting on YouTube or Vimeo, so it's all good for me.
Exported one animation as a series of PNG files and they all looked fine, exported quickly. Alpha channel was intact. So my workflow stands intact.

Granted this wasn't a stress-test, but the basics were covered and everything seems to be working as advertised.
ASP v10 runs in 64-bit mode on my Mac. So my verdict is that ASP v10 works as it should under Mac OS X 7.5 on my system. YMMV, however. My Mac Pro has a nVidia graphics card that replaced the previous one (an ATI, iirc) that died. Other than that, the Mac Pro is a stock machine. No hacks, altered ROM, no swapped out motherboard, whatever. Just 3 extra HDDs and a few added gigs of RAM.
Here's my specs, just so there's some kinda baseline (copied from System Info):
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Model Name: Mac Pro
Model Identifier: MacPro1,1
Processor Name: Dual-Core Intel Xeon
Processor Speed: 3 GHz
Number of Processors: 2
Total Number of Cores: 4
L2 Cache (per Processor): 4 MB
Memory: 6 GB
Bus Speed: 1.33 GHz
Boot ROM Version: MP11.005C.B08
SMC Version (system): 1.7f10
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Graphics Card is a NVIDIA GeForce 8800 GT 512MB
The key thing is that if your system can't run a 64-bit app, ASP 10 is not gonna work. In my opinion, if you're not running OS X 7.5, then maybe upgrading isn't going to work for you. YMMV, in any case.
(as an aside, whenever there's a poll from Smith Micro -- or any vendor for that matter -- and if you're using an "outdated" OS or older hardware, it's important to participate in that poll. This is a crucial bit for any developer to gain insight on their customer base, many decisions are based on the results. 'nuff said)
I'm in the middle of writing a book, I'll try to update this thread with additional info as I come across it as my so-called spare time permits.
Hope this helps some one out a bit.