As your ending suggests, older developers tend to rock the boat more. As their bosses tell them to do something, the old timers see failures of history repeating themselves and try to steer the direction elsewhere. Younger devs fall in line much easier.

It can sometimes be a double-edged sword. Some older devs get hung up on bikeshedding and tunnel visioning about old specifics instead of just getting work done with whatever the new environment is. However, this problem is far more represented in the big slow-moving corporate world, and go-getter active old timers looking at startups wouldn't generally fit that stereotype.

But if 2 devs are agreeably working on a complex project, the old timer will probably be faster to finish than the younger one. For non-complex projects, it's a crap shoot.