I'd be really worried if I hired someone that took 6 months to become comfortable with the ruby/rails (and rspec, rake, capistrano, etc). Now it might take way

I'd be really worried if I hired someone that took 6 months to become comfortable with the ruby/rails (and rspec, rake, capistrano, etc). Now it might take way longer than 6 months to fully master everything, but if you already have a good quality code base to learn from and a team of experts any smart developer should have no problem picking things up quickly.