There are a good many truths and there are a better set of likelihoods. Given the current state of dynamic languages today they are less performance than static and functional languages, however, it is also true that dynamic languages are more productive than static and functional languages. (I am not talking about savants)
Don’t optimize your code at the first stage. First make it right, then (if necessary) make it fast (while keeping it right). –erlang programming rules
It is likely that regardless of the size of your project, the size or makeup of your team, or the breakthrough that you think the project represents… that your project is going to have average results at best. The Google’s, FaceBooks and Twitters of the world are extreme edge cases. As proof, look at the iPhone app store. There are over 600,000 apps and only a very small fraction of those apps have the following that Angry Birds does.
So before you go off in a corner reinventing the wheel in your favorite language consider this. WHat is going to be your return on investment? I cannot blame you for learning a new language or tool that would enhance your marketability or even just for hobby sake. But if your intent is to make some money and maybe a little independence they you really need to consider your ROI. And if you’re making money then rewriting your killer app in whatever killer fast programming language is available (and popular) will make make plenty of sense.
This is why I’m hot on python and python’s django, tornadoweb, flask; perl and perl’s mojolicious; ruby and ruby’s sinatra and rails; redis, sqlite, zeromq.
PS: While I’m not a fan of erlang, partly because of what it represents, I really like it’s Programming Rules and Conventions(PRC). By comparison python’s PEP-8 is amateurish. The PRC starts off with ideas like the one quoted above and giving you ideas on how best to approach the problem. This is like python’s PEP-20 but again it’s like signing your name with a crayon instead of a fountain pen.