Not the greatest photo I know - but it was taken with my phone!
Here is my RNS510 A-version (which is currently living under my computer desk!).
The PIN diagram on my-gti is different to my one. It still has all the connectors - apart from that No.1 - DAB aerial input... although they're in slightly different places.
Judging by this, it must mean that the DAB tuner is built into the RNS / RCD - and if this is the case, you won't be able to do a simple swap unless you buy an RNS that has DAB built in.

I'd imagine this would only be available in version C units?
I'm not convinced by the DAB anyway, as the car I test drove with it didn't get a good signal hardly anywhere! Perhaps you should test out your one Kev before diving in and buying an RNS. If you don't get a great signal - then swap it for a standard RNS.
