We were there at the same time as the Pop Warner kids last year and there were large numbers of them staying at Port Orleans Riverside. We found the food court *packed* at breakfast. But beyond that, we didn't really notice them. They did not swarm the pool (although they did fill the whirlpool tub), they did not make more noise than any other guests, and although you saw them in the parks, there were few enough other people at the parks that time of year that the Pop Warner kids certainly weren't overcrowding anything.
Cheers,
Tara