Small tit-bit on Airplay, the new Mac OS Mountain Lion has Airplay specified (a specific additional option in the "add" drop down menu) in the Audio Midi setup as an output device. This means you don't need Airfoil. You can then stream any audio playing on the Mac (i.e. from ControlMac) to an airplay enabled device (i.e. M80 replacement). Bingo. Put an Airplay chip on a card for slotting in the 861/818...probably not rocket science.

It's the possibility of seeing them in Apple stores, keep the accountants happy...