We've used ME on three trips now and never had to wait more than 10 minutes for our coach to leave MCO. Although we are flying Virgin, we book ME direct on-line with our hotel confirmation numbers or via MS if we are staying
DVC.
On arrival at MCO, we pick the luggage up from the carousel, take it through customs and then deposit it to be taken to the B luggage pick up. ME get it from there, whilst we just head off to the ME check-in and get the coach.
We have never had to wait a really long period for the luggage to be delivered to the room, but just in case it takes a while, I tend to pack swimming kit in the hand luggage so we can relax in the pool even if the luggage hasn't arrived.
On the way home, we still take ME from the hotel, but we take a taxi to DTD to dump (sorry, check-in) the luggage at the early morning Virgin check-in desk, and then have an un-encumbered day before heading to the airport on the coach. Usually we spend the day at the resort swimming and chilling and then either dump the swimming kit in the trash or put it in the dryers in the laundry for 30 minutes before packing it in the hand-luggage. The early Virgin check-in means that we already have our boarding passes so the airport is also a more relaxing experience.
The main thing is to trust the system -- if you do, you can relax without lumbering around with your luggage. If you can't trust the system, or are one of life's born worriers, then you can still carry the luggage through the airport to the ME counter and know that your transport is taken care of. It's a win-win situation.