More than 40 is reasonable on an ongoing basis at a startup, but more than 60? more than 80? I don't think it's smart to expect creative people to work more than 50 hours a week on an ongoing basis. If they've got the requisite commitment and excitement then the other 62 waking hours will be well-spent subconscious time.

I'd not work 12 hours a day for a company, and then end up worse than if I had worked for a big company. If I would end up with a million bucks, then yeah, but if there is no advantage, I rather work for a big company then. As any reasonable person should.

Part of "reasonable hours" is not spending time on stupid things that end up being wastes of time. Obviously, this can be hard to determine in an early stage startup, but mostly this comes down to the personality of the other founders, that they aren't pushing for things that don't increase the chances of success or aren't constantly having the company change gears before finding out if the current route is going to flesh out or not.