We've been to Disney before and given a card on check in. They have never placed a hold on any of our cards. I know when we stayed at ASmo the limit was $500 and when we stayed at Port Orleans it was $1000 I think, so it makes sense that it would be $1500 for the deluxes. I think we had a $1500 limit when we stayed at the Poly but I can't remember! I do know that is has nothing to do with the limit on your card. We always leave our check card on check in-no interest, and a few years ago at ASMo, we only had about $250 on the card we left (we were only there two nights) and the limit was still $500. If they try to charge your card, and it gets declined, they will just ask you to come settle your bill with another form of payment, but this has never happened to us.
We plan on having plenty available on our trip this year, just was wondering the magic number was! Thanks!