Yes, DE is worthwhile. I rent from Dollar all the time and love the program.
As some airports, DE works like the EI. Alas, MCO isn't one of them. You have to wait in line, but it is a special line for ME customer. Usually, there is nobody in that line - and when there is it is much shorter and moves much faster than the regular line.
The best thing - IMO - about DE is that your paperwork is all preprinted. Nobody trying to push the insurance on you - no clerk typing a million things inot a computer. You just get your paperwork, sign in 3-4 places, and you are off very quickly.