"Best bet is to get some implementation. Most services fail due to lack of traction, not failure to scale."
can you elaborate on this ? what do you mean by lack of traction ?
thanks
Lack of traction means people not choosing to use it, and come back to it. If Mt. Gox had waited until they had a full featured socketed API, or DDoS protection, they may not have become such a popular exchange, for example. I would call this the businessman's answer.
This is so very much the wrong way to ask the question. Figure out what your orderbook design will be, and how you will make it consistent at scale. Your strategy for that will determine what databases or locking frameworks you intend to use, and then look at which languages integrate best with that infrastructure.
This is the engineer's answer.