I have been to three NESTs 2006, 2007, and 2008. Each time I went, there was at least 100 people, if not more. Many members of TT are also members on TMF as well and I know I met a lot of TMF members, but off the top of my head, I can't recall if I saw any TT members there.
Overall, it was a great experience. The people are really nice and everyone seems to have fun. One suggestion I would make before planning your trip is if you're a little shy or nervous meeting new people, make plans to meet up with some TT or TMF friends at NEST or FetishCon, etc. That way, you'll have some familiar faces (or screen names) to hang out with during down time, etc. Some people complain about feeling left out, but most people are really nice and easy to get along with. Knowing some people there beforehand though can help make you feel more comfortable.