Re: aftermarket radios - steering control compatibility.
I'm also thinking of changing the standard unit of my 147 to a unit wich will play MP3 and have an aux-in for my MP3 player.
The only hesitation comes from the effect on the Bose system in my 147 Selespeed.
After some searching only Blaupunkt and Alpine say they can operate (through an adapter) with the remote on the steering wheel.
I have yet to find a supplier and price but since blaupunkt is the "oem" supplier of my headunit i think i will go with a blaupunkt also.