Just my two cents, but I feel something of this nature would be taking a step in the direction of separating the forum into groups. And it certainly doesn't help the case of their being fewer domme females. We shouldn't have to create a special separate list for people based on their preferences, and worse, if it's a public list, then it just turns into a meat list for people looking for dominants.
I've never had a problem finding dominant or submissive partners. What there needs to be is 1) clear communication of expectations and desires in writing and story, and 2) clear indication or outline of preferences. If you have Player A say "I'm looking specifically for A, B, C" it will attract Player B looking for A, B, C.
I've encountered a bigger issue of people trying to claim they want A, B, and C, but instead really want D, E, and F. So they start with, "I want to play A, B, C, but now that I have your attention, how about we do away with that and do D, E, and F instead?"