I am also suspicious because I see threads asking about September crowds almost every day. I don't see threads wondering about August crowds? Maybe because people go in with the expectation that it will be more crowded. I know September has a reputation for being low crowds. We haven't been to WDW in 6 years, and we have experienced almost non existent crowds at times (we always go Labor Day and the week following). I know that the overall crowd level has increased by a lot over the last 6 years, so the crowds we once saw will not be the crowds we will see. (and having experienced DL a few times in the last few years I feel like we are much more accustomed to crowds now). I do feel like everyone is flocking to the early Sept. time because it has become well known that it is a slower time. But everyone going at that time means it isn't going to be that much slower. It might be slower than July (maybe), but it doesn't mean it will be empty.
I also think that there has always been a difference between early Sept. and late Sept. as far as crowds, but the entire month has been lumped as a whole of being low crowds. Even when we were going to fairly empty parks 6/7/8 years ago, it was still known that once the F&W festival started, the crowds started to pick up. Again, not to peak levels, but more than "low".
We will see. I hope I'm wrong and pleasantly surprised, but I am going in expecting it to be crowded. The fact that they are starting the DHS EMM at the end of Aug. makes me think they know there will be enough of a crowd to warrant it. The fact that they are continuing some of the summer events well into the beginning of Sept. also makes me think they know the crowds will be there to experience it. The fact that they are starting the
MNSSHP on Sept. 2 makes me think they are expecting enough people will show up for it. I know back in 2008 they did have the MNSSHP early b/c we attended and thought the crowds were very light. In 2010 they didn't start the party until a couple days after we left, which was closer to mid-Sept.
Anyway- I find it all fascinating and I know we will have a great time no matter what the crowds do (hopefully, lol). We also don't go in Sept. to try to avoid crowds, we go at that time b/c my husband can take off work at that time.