If you are really good at C++ (gork template metaprogramming, Alexandrescu's Modern C++ design) you will be as or more productive than most average people programming in Ruby or Python. Instead of focusing on the language think about the kind of people you are working with. Today you will find a lot of kool aid drinking kids coding in lightweight languages and quoting from Hackers and Painters at every opportunity. That does not mean they produce high quality software
That's not saying much in favor of C++ is it? If you are really really good at assembly you will be more productive than most average people programming in any language. That's because most average people aren't very productive at all.
But this wasn't his question. If he has what it takes to get really good at C++, he will probably get really good at Ruby or Python in that time.
I happen to work in a place where we use Python and C++, and I claim that for any problem domain for which higher level (lightweight?) languages are suitable, they are a clear productivity win over C++, for people of similar experience.
I agree that people are more important than language, but the choice of language also tells you something about the people. I suppose the poster has more relevant information about the people, though.
It also doesn't mean that they don't produce high quality software.
Remember, that when it comes to programming language choice, you often end up with programmer happiness (low ramp-up time to get something implemented) vs. performance.
It would be good to find out how open the place is to different languages. You may be able to write most of it in the language of your choice and only have to switch to C++/Java where necessary. This should especially be true at a Web-focused company.
