We have had a rental car, used a Town Car service with a grocery stop and used DME. We will use DME in the future. We don't need (or want) the rental car during the week, so we won't do that again. The Town Car service was convenient, but expensive.
DME is efficient and the price is right. We have never waited long and I agree with the 70 minute average. We usually check in around mid day and head out to Epcot for the afternoon. Our luggage has always been in our room when we arrived back, before our dinner ADR. I can't say how long it took, since we didn't wait for it, but it always made the room before we did.
We also use a grocery delivery service now (wegoshop.com) to deliver groceries to our room. The $11 delivery fee is certainly less than the Town Car service.
I also figure that if we choose, we could take a cab to a resort dinner, still saving ltos over the cost of a rental car. This might be the only time we would drive the rental. We use Disney transpotation to the parks.
All in all, I think DME is the way to go.
Have a great trip.