I updated my reliable Sandy Bridge build (GA-Z68XP-UD3, i7 3.4 gHz, Radeon 6870, Apple A1181 bluetooth module) tonight. I have a fusion drive setup, but the upgrade mostly went as expected. I cloned my home folder and non-app store apps, plus mail, to a functioning OSX bootable HD that I have in my build for emergencies. Then turned off Time Machine backups and proceeded with according to the Mavericks install guide. I did a "dirty" install, which means I did not reformat my drives and all of that, just selected my fusion drive and let the installation run. After installation, ran multibeast to install audio, 1080p setting, SDST, and Mac Mini 6,2 profile. Final step, as usual, was to extract files boot, boot1h, and boot0 from Chimera and write them to my fusion drive helper partitions (instructions from NeilHarts excellent Fusion Drive guide - Thanks again Neil!!). After that, it's all working well.
This time, no problems with my Radeon 6870. Sleep is working, audio is good. LOVE the new dual monitor capability in Mavericks...its about time.
Thanks to the TonyMac team for the installation utilities and great advice.