[kingfishr]

I don't know much about Django/Flask, but the arguments presented seem to apply to Rails as well. At my company we're moving off of Rails completely in favor of SOA structured architectures where the web views and APIs are built on Sinatra.

[tferris]

If you decided for Sinatra then I'd give Express on Node a try. Sinatra inspired, a large ecosystem with Node and very fast. Or: it's just a pleasure to work with.