Our ME experience was pretty good. We were able to check in to ME without more than a three minute wait (though that process needs to be speeded up a little - ours went very quickly because I was prepared and there was no line. There was a lot of other people who took ten minutes to check in.) We took carryons with swimsuits in them. We landed about 1:30 pm.
We were able to immediately board the bus, which was about half full. After about five minutes the bus pulled out and we were on our way.
BW was the last stop - which wasn't the greatest, would have been nice to be first - but the bus was comfortable and the Mickey Mouse cartoons kept the kids entertained.
Our luggage showed up within an hour and a half hour of our arrival - right into the room. One bag came about an hour later - one improvement I'd make is if they are dropping off part of a set to leave a note saying the remaining bags will probably be there in an hour, if they aren't, call. Since this is what bell services immediately told me (I suspect bags get split on trucks a lot).
Back we had to take our own luggage, as our airline doesn't have a checkthrough relationship. That worked fine as well - we left from AKL, and they picked up first, followed by a pickup at Pop Century. It took longer to get to the airport - lots of time driving around Disney property to get to and from Pop.
I would recommend paying attention to the luggage situation. If you arrive before mid-afternoon, there should be no problems getting your jammies and toothbrush - but you might want swimsuits anyway - pack a carryon if you think there is a chance you'll want a change of clothes or a swimsuit. When you pull into the airport at 8:00 at night, its completely reasonable to expect Bell Services to be knocking at your door at 11:00pm with your luggage. If that were me (I like to be sound asleep at 11:00) I'd handle my own luggage with even a late afternoon arrival.