I know many people feel like they get fewer comments over here (and the AO3 likewise) - I've never found this to be the case.

I've been posting fic for three years, and have used each of the three platforms as my main fic-posting place for some time. I seem to get the same number of discrete comment threads on any given fic: slash gets more comments than gen, Star Trek more comments than Narnia, but the choice of platform has never had a significant effect on the number of comments I receive.

Other people's experience varies, but, there, my two cents. :)