I finally got around to updating my i7-3770k build using the GA-B75M-D3H - to Maverics 10.9.1, naturally.
I'm dumbfounded with how simple it was. I created the boot USB as per the instructions, downloaded MultiBeast, downloaded OSX Mavericks and simply followed the instructions. Multibeast is a little different, but everything simply works, including audio, ethernet, USB, TRIM, infrared receiver (cobbled together from a Macbook Pro), bluetooth, sleep, shutdown, restart, etc.
I'm not sure what more I could expect given I started this process when I was on Lion and figured I might have to upgrade hardware between then and now. Nope, not even.
For those of you with sound or video issues, try resetting your bios to optimized defaults and starting over again with only the relevant changes. This is on revision 1.1 of the main board, FWIW.
Edit: The 'mute' function now works as well!
Edit: Ethernet suddenly stopped working after a reboot - had to repair permissions, now it's back. Pretty sure that was all me, as that's SOP after installing MultiBeast.