Turns out the problem wasn't resolved. For whatever reason, Aero got turned off during the driver installation. So the stuttering went away, but tearing appeared.
I gave up on trying to get it working. I'm actually using a different media centre so I can watch the 1080p24 content. When an official release of W8 comes out I'll try that as I understand that the refresh rate switching works properly. Or maybe it will work for me with something else (MP2, MP1.3, or a MS Service Pack).
Hi Doug,
I can talk about myself, i didn't get stutter @1080p24 after refresh change, i use Nvidia Card GT460. I think i can get stutter if i change refresh rate manually when video is already started (i need to confirm this on my 1.3.0setup but it was happen on 1.2.x). Maybe you can give a shoot on 1.3.0Alpha but there is also work for 1.3.0beta (not released except if you can build GIT Source).
I tried 1.3.0 Alpha. I'll try the Beta when it comes out. I'm not in a rush so I won't download and compile (as that would be a learning experience I don't have time for at the moment.)
I'm cautiously reporting that I believe the stuttering is now gone. I haven't had time to test it thoroughly though. I'll have to run it through its paces after/during the holidays.