At this point, I really couldn't back out if this startup even if I wanted to (and I have no desire to): I quit my job, spent a ton of money to move, and told everyone I know about my plans. As Dharmesh Shah of onstartups would say, I'm emotionally committed, which is more significant than my financial commitment (He has a good post about this at http://onstartups.com/home/tabid/3339/bid/1204/Startup-Founders-The-Involved-vs-The-Committed.aspx ).
As dfranke pointed out, we have more options than only accepting YC funding or not accepting. The real question is whether it makes more sense for us to keep going with money we have in Denver and find angel funding on our own, or move and take YC funding in a few months.
People who already have a lot of startup connections and experience probably don't need YC, but I don't get the impression that you are one of those people.
Again, not knocking YC, just weighing our options.
No the 'real question' is, in the words of pg is ...
'... Most of the groups applying have not stopped to ask: of all the things we could do, is this the one with the best chance of making money? ...' [0]
The article link is cactus. [1]
Reference
[0] pg, 'Why Smart People have bad ideas, A Familiar Problem'
http://www.paulgraham.com/bronze.html
[accessed thursday, 15 March 2007]
[1] The article link has a ').' appended to it so it gives a 404.
It's also important to understand that the 6% that goes to YC will be diluted by subsequent rounds of investment, and could easily end up as 1%-2% by the time they cash out.