Hmm, my 970 is noticeably dragging its heels in Yosemite, it's a way off the pace in Heaven and has been relatively average in the few games I've tested it in.. blazing under Windows though. It's funny how some are getting much better performance from the Maxwells than others. The i7-920 holds it back a bit I'm sure, but still.
Edit: For the sake of comparison, I ran the same test using the OpenGL engine in Windows 7 (I know, not a direct comparison but the OpenGL renderer is as close as you can get) and got almost double the performance. This is both relieving and thoroughly disappointing in equal measure...........