You already know a little bit of both, so why not just make the call yourself? I feel you already made up your mind and now you're seeking reinforcement. It's a technology trap and hurts your business. Good luck.
Also, every time I think about learning Rails deeper I think "damn, I already know how to do this on Node. Why bother..." but the industry wants Rails experience and every Rails developer I read loves it.
That's where the question came. Should I go with the current market or should I invest in a "promise" for the future?
Also, it seems to me you're starting your own company. Why does it matter what the current market demands then?