Did you guys do any analysis to get the 6 months number? Just curious -- I really respect the way you do things, so I'm wondering how much statistical thinking you put into your business.
otherwise, we use analytics, split testing and surveying all the time to drive business decisions, like what policies to set, what features to prioritize, content for landing pages/signup/referral flows etc. of course, we also listen to feedback and our own product intuition -- hard data is just one input.
sean ellis also helped us a lot -- see http://startup-marketing.com -- and i like dave mcclure's "aarrr" model (google it)