I worry there are people who didn't like us. We've now funded around 300 people, and out of that many there are probably some. But no group has actually told me so far that they thought YC wasn't worth it.
I think it depends on their exits. My thinking is if the startups have good exits, then they probably should be pretty happy with the experience. Can pg share a little stats on YC startups exits?
I'd be curious to know if pg and gang do exit surveys to find out what founders thought was valuable and what they thought could be done different/better.
At my Japanese employer salary assignments are done by grade and there is essentially no deviation for individuals. The company does not have managers ask engineers whether they are getting paid enough, because engineers rush to say "I am thankful for the opportunity to work here and am glad to be paid the same as every other engineer in my grade." I have said it myself.
Then once a year when they recalculate grades, they tell the I-can't-believe-its-not-a-union "Do an anonymous survey and tell us what people actually think." They even follow the recommendations a portion of the time.
I love your stance on not doing anything formal. But if you took an anonymous survey of all the American engineers at my company, you'd probably hear "Do anonymous surveys or people will give you the answer they think you want to hear" from 100% of them. (Population size: 1)
Also, convenience samples have some well-known issues: if somebody was totally soured by their experience and cursed your name, would you still be talking to them on a regular basis? (My company has the same issue with its salary survey, incidentally: the people who are most dissatisfied with the amount of money offered no longer work here. Funny how that happens.)
Even if you had a bad YC experience, it wouldn't be to your advantage to go public with it. You'd burn bridges for little gain.
The only people who seem to bad-mouth investors are ones who've already made more money than they know what to do with (Sabeer Bhatia style: http://www.foundersatwork.com/1/post/2009/02/a-note-about-sa...). YC hasn't had any giant, mega-hits yet that would warrant a founder poisoning their relationship with the investment community.