Chris - what was the spec of each? Both manual? Both DSG? One DSG one manual?
The mpg differences could be likely with a manual R vs a DSG GTI.
Did they both have (or not have) DCC? I find my R's ride (on Prets) a little harsh crawling around in traffic, but really smooth above 20mph, without DCC. Ride differences could also be down to the rubber each had and tyre pressure differences - Bridgestones that came with my R were very much harder on the ride than the Michelin PSS that replaced them.
Did you get the opportunity to give it some welly? Assumiing you went to Lookers Silverlink, all those poxy average speed cameras that have cropped up around the Silverlink roundabout in all 4 directions might not have given you much of a chance to stretch the car's legs if it was just a short test drive.
My mobile is dead at the moment - needs a charge, so will not have seen any messages you might've said on the subject.