> It seems that a lot of startups say they value life/work separation.
Of course they say so. Deloitte says so too, and Wachtell, and Cravath, and every other high pressure professional outfit. Doesn't make it true.
> There has also been research to suggest that working that much is anti-productive.
Yeah but most of those are in different circumstances. It all depends on where the motivation comes from. If you take a wage slave and whip him into working 80 hours, while paying for 40, and not dangling any form of carrot in front of him/her (making partner), of course productivity will go down. If you've got a product you believe in, a vision to make it come true, an innate drive to succeed no matter what, and no personal life, you can work 80 or 100 hours a week for months on end and get the work of 5 or 10 people done in that time.