[seanmcq]

One of the biggest costs of a NoSQL solution in an early-stage startup: what's hot today may be abandoned by everyone else by the time you're a real company, leaving lots of effort inventing clever solutions to novel problems created entirely by your data.

It's much more feasible to start with a solid database and add caching for hot data than it is to try to build a company and a brand new database technology at the same time.