He's my boss, so I'm super biased, but I can still share a primary-source perspective. I knew him for years before working here, and would say that both as a manager and a general human being, he's one of the genuinely best people I've ever known. From when he started Fogcreek, his and Michael's whole philosophy was to create an environment and mission that makes smart people actually love working there, and then get the hell out of their way. Here at SE, we've grown a ton since I've been here, but I can tell you our exec team spends a lot of time discussing how to ensure we maintain an environment where employees are actually excited to work. (I know that sounds goofy/cheesy/like BS, but talk to any of our devs or other employees; I think you'll find that just about all of us take great pride in what we do.)

As a startup entrepreneur which don't doubt about success and growth -- how could I ? ;) -- I am very interested in the work invested by the whole team in a sane and enjoyable workspace.

What are the trade-offs ? I always feel like only the exceptional rich companies can sustain such high standard of living, the same rich which will respond that it's the only way for keeping an healthy work in the end.

Seems like a never ending chicken and egg problem that I don't have time to solve, I have hard deadlines to manage... (it's slightly exaggerated, of course, but you got the picture)