My family and I were at Disney from Sept 5 -11 last year during
free dining. We had such a fantastic time we are going back again Sept 10-20 this year.
After Labour day when every school is officially back in crowds drop off dramatically.
Resorts are busy and if you don't have ADR's your pretty much out of luck for TS meals.
We found very short waits for rides. We used only 3 fastpasses Soarin, Toy story Mania and Kilaminjaro Safaries.Often the time posted on the clock was not accurate at all. We would walk right on even if it said 20 minutes.
We walked on many rides and we did
MNSSHP and that evening we rode the same rides multiple times without even getting off.
There are crowds for shows,parades etc. Don't expect empty parks(that would be creepy) . We never did EMH , we didn't need to! But we did get to parks for rope drop so we could go back to our Resort for a rest and swim before heading back to a park or resort for dinner. That plan worked great and we will do the same this time.
People there now are experiencing big crowds because free dining was offered at the end of August and many people are getting there holiday in before the school year begins. With the economy the way it is I expect the crowd level to be the same as last year if not less. Free dining has never been a secret and was heavily promoted in past years just like this year. The only difference is they have extended it to December.
You will have a blast.