I think I referred as "comparative advantage" to something different from what you mean. I was speaking to the advantages of the person hitting on someone: all else being equal you should focus on fora where your skills come to play. If that forum is large enough (like OkCupid), I think it makes sense to focus on that exclusively. In any situation where you meet potential dates specific skills matter and some people are better than others.

For example, I'm at a strong comparative disadvantage when hitting on people on the subway because I have a really goofy accent that people don't expect from my appearance and it lconfuses them. Someone who looks hot and has a great voice will do well on the subway without needing any context or background info on the person they are talking to.