Hackathons wouldn't satisfy the OP's requirements for complexity, nor demographics - you'd be looking at a self-selecting group of highly motivated people, skew

Hackathons wouldn't satisfy the OP's requirements for complexity, nor demographics - you'd be looking at a self-selecting group of highly motivated people, skewing young, who would come together hackathon style. There aren't going to be many thirty- or forty-something coders with young families spending a weekend (to work on the same set problems as everyone else) at the hackathon, yet there are plenty of those in industry.