I've been following this thread since I upgraded to Yosemite. I have a 15" MacBook Pro Retina mid-2012. As soon as I upgraded to Yosemite, I started having graphics issues, freezes, reboots, up to 10 times a day. Before upgrading to Yosemite I never had an issue. I tried all the fixes, locking the graphics to one card or the other, reducing transparency, etc.. I could no longer use my laptop at this point as it would continuously reboot. I also rolled back to Mountain Lion (and Mavericks) and experienced the same issues... I also waited until 10.10.1 came out hoping that would help, it didn't.
With no other options (and since I had Apple Care) I made an appointment at the Apple Store. They kept the MacBook and called me a day later and said they were sending it off for repair. I got it back 3 days later and I have not had a single lockup/freeze/reboot in 4 days. They replaced the logic board and a hard drive cable (this wasn't listed on the repair but the guy @ the Apple Store said they did). I should also add this is the second time my laptop has had the logic board replaced. Not sure this is the exact same issue you guys are seeing, but thought I'd add to this thread in case it helps anyone.