I wouldn't place too much importance on this group. It's obviously a socially and/or politically motivated thing. Whether or not these people claiming to have "chosen" to be gay are actually falling in love with members of the same sex or enjoying gay sexual relations in their private lives remains to be seen.
Like the ex-gay movement, these people seem to be representing a social point of view and pushing a theoretical concept, rather than expressing what is actually in their hearts as individuals.
As for me, I've always been a homo, and I definitely didn't "choose" it. There are times when I would have preferred to have been given a choice.
Then again, being different from the mainstream has given me all sorts of insights and led me to people and places I never would have dreamed of. It's also given me a deeper understanding of the story of Jesus that I don't think many straight people will ever be able be able to fully grasp.
It's been a long, strange trip. I'm personally grateful that God made me gay. I wouldn't give it up for the world.
-E