So much for my mouse problems disappearing. There are dangers to being an early adopter.
I considered myself lucky that I hadn't suffered any of the truly horrendous game over problems being reported by other Yosemite Beta testers in the MacRumors Forums, but the mouse issue I'd previously reported had become intolerable. It had reached the point that not only would it spontaneously disconnect, it was often taking two or three reboots to get it to reattach itself. Way too much trouble.
Time to abandon Yosemite in its current state and revert back to Mavericks.
The reversal process wasn't a walk in the park. Even though I'd dutifully backed up my Mavericks installation to Time Machine before I loaded the Beta, for some reason after wiping Yosemite and reinstalling Mavericks from scratch, Migration Assistant couldn't actually use the backup. "No valid volumes found."
Ugh.
Thankfully I'd used Carbon Copy Cloner to create an image of the entire Mavericks drive around the first of July and was able to successfully restore from that. As for data that's changed since then, I was able to manually transfer everything back from my latest Yosemite Time Machine backup.
I've learned my lesson. I can wait for the general release. October isn't that far away.