We have taken our 2 daughters at various intervals, the younger one first went at 6 mos and now we're taking them back again this Sept/Oct at 18 mos and 4yrs. I have to say that it's a lot easier to take a baby/toddler *before* they start walking! So, if your 10 month old is not walking yet, this may be an ideal time for him to go. Our 6 month old happily stayed in the stroller or a baby Bjorn all day.
When we took our older daughter at 12 months, it was a very frustrating experience for all of us! She was not truly walking, but was crawling everywhere and pulling up and she HATED the stroller. There are not too many safe/clean places for a baby to crawl around at Disney! She would occasionally consent to being carried in a backpack (the kind where the kid looks out over your head), but *I* had to carry it, not daddy, and it was soon straining my back.
So i'd say whether you take your baby depends first of all on his temperament and secondly on whether he can walk!