I have done the internet search thing and the phone call thing and researched several companies about an
ECV for my DH. We decided on off site rental for a few reasons:
1.) Availability...we know that we will have an ECV every day we are there, no matter what time we arrive at the theme parks.
2.) Park Hopping (it is my understanding, although I may be wrong) that you can not take an ECV from one park to the other...you have to turn it in and get new one at the next park...I could be mistaken though
3.) Long parking lot walks.
4.) It is also my understanding that Downtown Disney doesn't rent
ECVs
5.) We are also going to Universal, and again, you can't take an ECV from one park to the other.
6.) We have also read on this site that the Disney ECV's have governors on them that control their speed, and they go much slower than other rentals. We are not looking to race around WDW, with me pushing a double stroller, and our 3 other walking kids in tow, but if my DH needs a little more power to get up an incline, it is nice to know that he will have it.
Hope this helps...BTW, all the companies that I talked to would deliver it to your WDW resort and pick it up. It should be there waiting for you, if you choose this option.