We were also there last year on the Gay Days/Miley Cyrus weekend. What I found was that Thursday, October 2, was crazy busy in Downtown Disney - it was as busy as if it were a Saturday night. Friday, 10/3, we spent all day in DCA, only popping over to DL for dinner and then headed right back to DCA for the TOTP. It was not unusually crowded. On Saturday, October 4, the first 3/4 of the day was okay inside DL and we didn't notice the crowds to be too much. But Saturday night, however, it was packed, and lines that had previously been 15 minutes jumped up to 50 minutes and things like that. Also, Pirate's Lair was closed as they built the set-up for Miley, so that was one less place people could go to get away from crowds. Sunday, 10/5, DTD started to get really crowded around noon, so I have a hunch people were already packed into DL for Miley's b-day. So overall, with the exception of Saturday night, we didn't find the crowds to be unreasonable at all.
Also, 'crowded' is kind of a perception thing too. What one person finds to be too crowded or unbearable may not be what another person finds to be unbearable. We also went to DLR for the last two years on the weekends right before Christmas, and while there was certainly a healthy attendance level both years, it didn't bother me too much. Other folks may think it's outrageous.
The only times I have been to DLR when I would say the crowds were TOO crazy for me were New Year's Eve of 2000 and Thanksgiving weekend of 2001, with NYE being the worst, of course.