Here's some advice, if you think that schedule is intense, you're not ready for a startup...
Its ok if you roll in at 10am, spend an hour horsing around on Hacker News, another hour drinking company beer at 7:30pm, and another hour at lunch running with folks, you are "dedicated" and "intense".
Nevermind that you spent less time working that the OP - you have to have no life outside of the startup to be "intense" and "startup worthy."
For me, I'd rather have the poster - he sounds like a great employee - works hard, contributes outside his area, and seemingly has a life outside of work that probably rests his brain such that he isn't constantly exhausted like you.
If you don't get into Y-Combinator, contact me.
The fact that the OP was able to grasp this particular issue so early on shows a maturity and insight that even senior engineers who go to work at startups might miss.
I know I've had my moments.
I won't lower myself to respond to personal attacks which fill the rest of your post.
Peopleware should be required reading in startupland.
Also, I've been hearing about Peopleware a lot recently. Thanks for reminding me.
And this is symptomatic of author's lack of experience. Prodigies excepted, a person right out of school probably doesn't have sufficient knowledge to accurately diagnose business processes, marketing communications, and UX design paradigms holistically.
Letters don't always need to be pitch perfect and early versions of solutions sell on problem solving, not interface design.
More importantly, many true startups have a business model that is fundamentally flawed without considering the potential for large infusions of outside capital. That's why most crash and burn.
That's not to say that leaving a place where paychecks bounce is a bad idea. Assuming one is the smartest person in the room, however, probably is.