I went back to college marching band, I'm lucky I'm a part of a great organization so it wasn't a massive change. But, most the comments I got were that I was much thinner (about 20lbs) and a lot bulkier (since I'm a girl and carried around a contra all summer).
The thing that killed me though was the breaks. I'd be ready to go back out in 30 seconds, and people were just walking to the sidelines, takin' a seat, eating some food...we had like 7 minute 'water' break, I was driven crazy!