Choosing a cab vs Mears shuttle is going to depend on your party size. A cab will be about $35-40, each way....so $70+ r/t. But if you have more than 3 people, that may be your best bet. The Mears shuttle is $20 pp r/t.
I've used the DU deal a few times. There was one year that my friend and I actually took the shuttle bus to US/IoA on a Wed, and took it back to BWV on Thursday. We fot a great AP rate at RPR. Packed up our backpacks and took the bus both ways. We got to US/IoA about 7:45, got checked in at the resort, and were back at the park entrance by 8:20. So got to get into the park a little early. When we were ready to go back to BWVs the next day, we just called Mears, told them when we wanted to leave. They told us what time to be at the bus stop for an available bus. Actually were able to get a bus 90 mins after calling! We needed a bit of extra time to get back to RPR to get our backpacks, otherwise we could have gone to the buses when we called...there was a bus for us 30 mins after calling.