They might slow the development down but to what advantage? Better design docs, better func spec, better docs, better quality. If your startup has a room to g

They might slow the development down but to what advantage? Better design docs, better func spec, better docs, better quality. If your startup has a room to grow, this is one option to go. You don't just hire all developers and hope your software doesn't have bugs. Cowboy code a.l.a Agile (the bad Agile) is very dangerous and this is what some people warn these young startup people. The whole RoR (or Python/PHP, whatever) + Agile is like playing with fire; if you know how to stop it, you're in a great shape, if you don't, it'll burn your product faster than any other mistakes.