We were there from Dec 6-11 and had little problems with Pop Warner / Cheerleaders. However, we were staying at AKL (got a code, just had to do it) While we did encounter football teams in the parks, the ones we say were quiet / behaved and in general, good citizens. We did see some not as well behaved cheerleaders, but in general, had no problems with them either.
Last year, I stayed at ASMu and did have more issues with the cheerleaders, but not enough to keep us from coming back at this time of year.
The benefits of having short lines, less crowds, moderate temps,
MVMCP, xmas decorations, etc. outweigh the inconveinences of naving these groups present. I will absolutly continue to go at this time of year.
Remember that you are at Disney and have many choices of entertainment, if one venue has many groups of screaming cheerleaders, go elsewere. Most of these groups stay together, getting away from them is usually easy.