We were at POR from 11/30-12/4. There were several Pop Warner groups that arrived on 12/2-3. I didn't notice much of a difference with the crowds in the parks toward the end of th eweek. We mostly saw them in the food court in the morning and in the evening. They were a bit on the rowdy side and a little inconsiderate in the food court. It definitely impacted the wait times for ordering meals, but other than that it wasn't a problem. You should be too affected at a deluxe. Most of the teams stay at the values, POR/POFQ and maybe one of the other moderates.
As for the parks, most of the wait times were under 15 mintues. THe exceptions for us were, Peter Pan, Dumbo, Thunder Mountain (all between 20-40 minutes), Test Track (1 hour, used fast pass with a return time for 50 minutes later, waited in line for 10 minutes) and Soarin' (170 minutes stand by, fast passes were gone we we got to EPCOt AT 3). We took advantage of teh EMH hours and were able to do alot during those times with minimal waits (Atro ORbiter was 5 minutes, Adventures of Pooh was 10, Dumbo during morning EMH was 10). The beginning of December is also MouseFest (big informal convention of various discussion boards/web sites). THis can also increase attendance at the beginning of the month.