I did the DD about 3 years ago. For me, it was something I was glad that I did but I didn't want to go back because I didn't enjoy it very much. It is a ride designed for natural climbers and I am not one. However, I enjoyed the descents. It was by far and away the hardest ride I have ever done. Except for the last 20 miles on the DD, it was a constant up and down. Never a flat spot. You can't train too much for it. My arms and hands really hurt afterwards from all the out of saddle climbing. When I returned to the hotel I saw a guy walking backwards down the steps.
The starting town leaves a lot to be desired. Few decent restaurants and lodging. I stayed in the WISP hotel and it is a ski resort that has seen better days. Deep Creek lake is pretty but packed with summer homes and cottages for the Washington DC folks. Although they call it a Gran Fondo, it isn't timed. The route was nice and the support and rest stops were very good. I remember going past one young lady squatting in the middle of the road at the top of a climb. She was down so low a car could have driven over her and not touched her. I asked if she was all right and she just said "I'm peeing." I took her word for it.
When you get to Westernport somewhere on the latter 1/2 of the route you come into town at the top of a steep street blocked off by a guardrail. The route turns right and you don't go down the street but instead circle around to the bottom of it. Then proceed through town to a rest stop. If you want, turn left at the bottom of the street and try climbing up. It is short and concrete that is all broken up because it is slipping down the hill. The road is used in the Savageman triathlon. I made it up while a couple rednecks drinking beer on their front porch cheered me on, hoping I would fall over.