I've had fantastic results. On one hand, many of my customers are MDC mamas. This allowed me to do a lot of sales during the time when we weren't listed well with the search engines. It also seemed to help my search engine rankings (I suspect this is because the posts are dated and MDC is well indexed by search engines). Within 6 weeks, we were getting orders from search engine customers.
The only caveat of course is that you have to post and post often. It also helps to frequent a number of sub forums (rather than just a couple).
It's kind of a fun way to promote my business because seriously...like I'm not going to be hanging out and chatting on MDC anyway

Hope that helps
