Great post, with some very interesting ideas. My experience has been that although it sounds great to be "super" flexible, it's really hard to run a company that way. As you add more people to the team, people will mimick the worst behaviors to restore fairness - "if jon always leaves at 5, then it's not fair if I stay late" and suddenly people start slacking. Strengthening the rules later is also really hard, but at some point you realize you have to.

That doesn't mean you push people 60 hours or weekends, but you enforce minimums like 9-5 and you make sure everyone feel's everyone is equally contributing and that everyone is trying hard.