Great article and a very sweet setup indeed. I just have one comment regarding this:
AirFoil: In part so I can stream Rdio to my Apple TV-connected stereo, but also so I can manually adjust the EQ for Rdio, even when just listening on my computer.
AirFoil is not needed to stream system-wide audio to the Apple TV. OS X can do this natively over AirPlay by holding the Option key, then clicking on the Sound icon in the Menu bar and setting the preferred audio output (in this case, to Apple TV). See here for more details.
However, you’d still need to use AirFoil (or any other system-wide EQ app for the Mac) to manually adjust the EQ, since AirPlay doesn’t currently support that feature.