I doubt SEO effect would have a prolonged impact on your site. Numbers on referral traffic cited on Quora range from few thousand to 15K visitors. Not that much.
There is much better potential upside though. TechCrunch is being read widely so it's your chance to get to know your potential customers, employees or VCs. That's valuable.
I know a Boston developer who had a very simple beta site mentioned in TechCrunch in 2009. It generated about 35,000 site visits in one day. It eventually got about 70,000 users. The developer eventually pulled the plug when he couldn't convert enough users from free to paid.
SaaSy.com's launch was covered by TechCrunch on March 17th. It was a generally positive, comprehensive article, "Online Subscription Billing Is Still A Hassle, SaaSy Aims To Change That":
http://techcrunch.com/2011/03/17/online-subscription-billing-is-still-a-hassle-saasy-aims-to-change-that/ It resulted in about 2,000 unique visitors to SaaSy.com via TechCrunch, according to Google Analytics. That led to about 65 new client signups. While this is valuable, my feeling is that the best value from TC is the branding. It puts you on the map overnight if your target market overlaps well with the TC readership. TC was our top media placement target, and we're pleased we received such nice coverage.
The advantage comes from the high domain authority of TechCrunch. The page will appear high in a google search of the keywords in the article and the backlink to your site adds more than the average backlink to your domain authority.