I have just returned from the Baehr - Garmin dealership. BTW they lent me a KTM Supermotard. I came back home with a huge shit eating grin on my face. What a toy !!!
So, the Garmin cradle DOES exist. However in order to be compatible with the 2720 it needs to get a software upgrade. It seems Garmin didn't expect such a succes, so no upgraded cradles available for 6 weeks. What's even weirder is the fact that no 2720 is available. Production can't follow demand.
Regarding the RDS receiver. The 10 is for putting behind a radio. The 11 is to work without a radio, it only receives the RDS messages and transmits the data to the 2720 via its USB port.
The idea is to mount the Garmin cradle on the BMW holder. As soon as it's done, I'll send pictures. So far, none available of the cradle.
The cost of the whole installation including the RDS module is about 1600 €. That includes everything you need to use your GPS in the car as well.
These guys do a VERY clean job, and they are very correct people.