The only time I have gotten to my resort faster using a towncar service rather than DME was the one time I had no checked luggage. I had only carry-on with me, so when the driver met us in the baggage claim area, we were able to just head out to wait for him to bring the car around. That trip took us about 45-50 minutes from deplaning to resort check-in. The times I have used DME, with checked luggage and without, it has taken 70 minutes or less. When I have had checked luggage and used a towncar service, it was about 60 minutes to the resort.
If I can save $120 by using DME, then I'm happy. Even if it took me a little bit longer to get to my resort it isn't a big deal. What's 15-20 minutes in the big picture!