I believe the culture does allow organic life to upgrade to a culture mind. I think I read that somewhere. Of course you wouldn't be you anymore, but you have options and that always made it a pretty malleable cage you can slip out of including just leaving.

So you still have freedom of self...just not much power to shape your civilization. Most of us don't have that anyway and at some level I think I'd be ok giving that up to a group of super intelligences so I can spend more time doing the things I enjoy.