I have been in May when the main competition was going on. The cheerleaders and dance teams was mainly at the value resorts and I was at the All Star Music Resort as well.
So, this is how it was, THEY WAS NOT A PROBLEM, very well behaved, parks not impacted a bit because they was at ESPN cheerleading, Disney plans for them with more buses and more help.
The resort pools was not crowded with them at all, you see them mainly in the morning eating breakfast but always plenty of room. In fact, I thought it was a extra bit of fun that they was there.
They are from all over the world, talk and dress different and some of the costumes was fun to see. If your going look forward to it as added enjoyment.