D&G has a deservedly excellent reputation for mountain biking. The 7 stanes trail centres offer some exceptionally fine riding year round. Mabie forest is particularly close to my heart as I it's where I first started mountain biking. The current red route trail there still encompasses many of the trails we used to ride on our fully rigid MTB's with canti brakes! Things have moved on somewhat. I now have Dalbeattie forest as my local trails and absolutely love it. Expect a few posts about XC mincing around there!
What I think is most overlooked about D&G though is the road riding. There is a huge network of quiet back roads that are virtually traffic free. The scenery is varied, from open coastal roads to rolling farmland and up to exposed, windswept moors. After the riding around London it really is a breath of fresh air (in more was than one) to not have to dodge and weave through traffic for half an hour just to get out onto a quiet road.