I don't really think of myself as a rare pair author, but by your definition I am. I don't right Snape/Harry or Draco/Harry because they don't really interest me. I can imagine writing them because I had a bunny or I was challenging myself or it was for someone I knew reallyreally loved the pairing. I cannot for the life of me imagine writing it because I would get more feed back.

Remus/Sirius I haven't written yet, but I do love. Still, not forcing myself to write it just because it might get more attention.

Of the pairings I do write, I have not felt the desire, for example, to turn a Ron/Draco bunny into a Ron/Harry story simply because it is more popular.

Now, the caveat is that I've never got much feedback on anything. Maybe I don't know what I'm missing, and if I got recognition I would fight to keep it by any means.