I don't have a aftermarket deck but yes you'll lose your steering wheel controls for now. Pac-audio is suppose to come out with something but no word on when. A fellow member (JonW) is working on a CANBUS module as well.
My last e-mail correspondence with Brett at Pac-Audio was a couple of weeks ago and they hadn't made any progress on theirs. He said he was interested in what I was working on but I haven't received any replies back from him on my last e-mail on the subject.
If anyone has any links on control protocols for the Alpine or Pioneer units, I'd be happy to take a look and see what it would take to make an interface. I've already done the CANBUS side so it would only be a matter of writing the aftermarket interface side. Do most of the high-end aftermarket units have a wired control port or infrared?
I'm sticking with the factory NAV so I haven't looked at any of these other units.