I'll answer yes, but with a qualifier. I don't necessarily think IQ tests alone are an accurate gauge of a person's intelligence. Some people, including myself, do not test well. That said, I graduated with a 3.85, and left graduate school with a 4.0. If I had a choice to write a paper or take an exam, I always opted for the paper.

So far, my experience with those interested in bdsm are highly intelligent and well-spoken individuals. I also find many excellent writers among the bdsm crowd. I think you might be onto something with the fact that bdsm has more of a mental element to it than pure physical sex.