the best time to go with the least amount of kids is when school is back in session. 800-1500 kids may seem like a lot when looking at the numbers but once on board its not. i've heard many comments on other boards about how well Disney does with adults only places. Also when on board you'll be amazed that there are that many kids on board for you hardly see them. The kids really don't get "out of control" because there is soo much for them to do.
hope that helps answer your question