I too gave up the Limo services when I replaced my manual with a powerchair. I have used Mears the last four or so trips (plus a side trip to Universal).
I have no complaints whatsoever. Their wheelchair vans carry just two chairs plus say four/six extra family members plus luggage. Three of the four trips (seven out of eight one way trips) my wife and I had the van to ourselves, so we had a direct service. Just as good as a limo, but without the cost!.
The one time we shared a van it was with another wheelchair user and we had a great time chatting, so I didn't mind the slight detour on the way to my hotel.
Six out of the eight rides we have had the same driver, and it is always great to be met by someone you know.
Just the once we had to wait a little longer than we might have done with a limo, waiting for a wheelchair van to arrive - maybe 30 minutes or so. But then, it's vacation time and hanging out breathing the warm Florida air is part of the fun.
Some of the cabs in Orlando are wheelchair accessible (Ford Galaxies with lowered floors & rear entry ramps) and you could use one of those, but I don't recon they are worth the extra cost. For a photo, follow this link
http://www.wdwinfo.com/photopost/showphoto.php?photo=875&papass=&sort=1&thecat=577
Andrew