My sense is that the forum primarily serves people who have come to haiku only recently and wish to
learn more. In that, it does a good service. I don't get the impression that many of the more "established" writers come here, though occasionally one sees posts by Paul M, Lorin Ford, and a few others.
On Troutswirl, features like Richard Gilbert's "Creative Blooms" does stimulate some discussion, though
it has been a while since he has offered something new. (Which is understandable-- clearly a lot of work goes into it). Sadly, re:Virals has not lived up to its potential.