" I can't figure out what is going on with some folks and the high frequency distortions, though. I had this issue the first couple times through running Audyssey, but changing the mic positioning from the standard recommended spots to something lower actually cleared that all up."
I had the high frequency boost until I changed the mic position from the recommended ear height (which put it just barely above the chair back) to a couple of inches higher so that there were no reflections from the two heavily stuffed La-Z-Boy chairs in the middle of the room.
It also gave me more balanced speaker level settings. Before, it always set the right speakers, 7.1 wide's, 1 1/2-2 dB higher than the left, which was puzzling as the room is identical on all side/front/back walls with no other furniture other than the 2 chairs. Now, all my speakers are at the same level and the sound is perfectly balanced with no harshness at all and the clearest, tightest bass that I've ever had from Audyssey, MultEQ in the 707, and now XT32.
I was obsessed with trying all sorts of remedies, speaker height, toe-in/out, etc. and would run the calibration daily with no improvement...until, just raising the mic solved all my problems and I haven't messed with it in over a month.