Hey moarfish, are you saying that the only way to get Yosmite installed is a clean install, similar to Mavericks? I see you updated your original post, but it looks like a fresh install again. ouch.
Its the part in bold that confuses me,
10.10 Yosemite Update
1. Download Yosemite, Create USB using Unibeast
2. Boot from USB, Disk Utility Erase the old Mountain Lion boot drive.
I have not tried to update on top of Mavericks. I always try to clean install when a new OS comes out for perfect performance.
Finally get time to install following Moarfish settings for Yosemite, everything went fine, all working. Still not USB 3.0 but ill try some kexts.
Thanks Moarfish.
My specs are:
GA-H67MA-USB3-B3
Intel Core i7 2600 3.49
Gforce 9800GT 1GB (OK)