I turn 48 in July and am the Indy Moonhead and still compete in tournaments as well MMA. I'm one of the older Moonheads. i think there are a couple older than me.
As far as technique selection, I don't think it's age based. I think everyone has their own style based on their ability and success. Flexibility does play a part but not due to age. I'm more flexible now than 30 yrs ago when I was in high school and hell, look at Eddie, he's a few years younger than me and look how flexible he is.