I've done exactly the same. As much as I hate to say it, if the local VW stealer had done his stuff I would be in a Mk6. But as it is, he showed very little interest and I'm now in a late 09 320d m sport, with the right toys for just under £22k. Alright not as fun, but the cars 5 months old, done 4k and cost £33k new list price. With my mileage going throught the roof at the moment, I'm not complaining at 60mpg compared to my Mk5s 25mpg.
Quality and price compared to the Golf don't match and unless the VW Dealers start letting you test drive the MDs Wifes Car - sorry demo - then people will move out of the brand.