My system is actually working with Yosemite. Not as it should do, still.
I can revert anytime to my old Mavericks install and also go for a clean install of Mavericks having had made bootable installer disks for both systems. I don't think this time is a problem related with hardware, but with the software instead.
When I had to change the logic board the system wouldn't even start in target mode at the Genius Bar.
Though no big deal with that, aside of the annoyance of putting everything back in place. And spending time on it instead of actually using it. Something that if I loved to do (as many other people do) I'd have chosen a Windows or Linux system and then spend my time with configurations, latest drivers, etc. Not on a Mac. Not on a PRO machine.
Let me say that I haven't seen a kernel panic in about 8-9 years 'till now…as well as all this troubleshooting… never ever needed to do it on Mac OS X. Maybe on 9.
BTW all this stuff is far from what Apple products expierence have been for the last decade. Including not having the MBPro logic board failure recognized as an issue by Apple despite it happened to so many customers. Getting back even half the money I had to spend for that would be better than zero at this point, this is why I signed for the class action. I don't like to do speculations on Apple's policy, having never had a single problem with the quality of their products 'till this MBPro. Though I don't agree with your "wonderings".
You're welcome about CCC.