If RPS become a problem you can probably switch to JRuby. I did exactly this 15 years ago for EUs biggest software company and it worked out quite well.
Have you seen the latest state of JRuby development or seen the posts of its development team. If you are comfortable with the idea of your main runtime being dependent on the time / finances / availability of around 5 (or less) core developers I would say you are ok with JRuby.