They're pretty good in my experience, I definitely think it can make a huge difference.
For the last few years there's been a big campaign to get people back into sports they may previously have enjoyed at school or pre-children; sports clubs like mine have really picked up the baton and it's making a difference. Every season we have new players coming into our competitive teams off the back of our "back to..." sessions.
If you tell a sports club that coaching this way or that way will increase the number of female members, either in childhood or adulthood, they're usually game. Members = subscription fees, = a higher club profile, = more successes, = all sorts of things sports love.
If girl-centred coaching techniques encourage girls to keep up a sport, the sports clubs will undoubtedly oblige.