Thanks for doing these extensive benchmarking tests. It would be really helpful to see a more complex example that includes user authentication. Aside from the benchmarks it's also a really good starting point to compare the code in different languages and get a first impression of a framework. On a side-note, I'd really like to know why so few start-ups seem to be using Spring. It could be just a wrong impression .…
I've used spring mvc in an agile setting a couple times now, and it has worked fine. It doesn't tend to make developers all that happy, in my experience. If you're in an enterprise full of spring, starting up the next app with it can be attractive -- there likely already exists a bunch of tooling and knowledge around spring.
I wouldn't use spring directly if I were trying to build something quickly for a startup. I'd be more apt to reach for grails (which wraps spring), dropwizard, or any of the other rapid-development frameworks.