The biggest risk when going with a long established solution is the potential danger of picking something that is on its way out of the zeitgeist. Not that picking your tech stack should be a popularity contest (and in fact many people make the wrong choice by chasing trends), but picking a component that has been left behind can have some real consequences (e.g. might become increasingly harder to find good talent for it).

But your post mentioned RoR is having a bit of a renaissance. Its maintainers are still invested in it, and there’s enough of a community that you’ll find support. To me that sort of answers your question.

I’ll also say I’ve learned to take opinions about technologies on HN with a grain of salt. You’ll often find someone gushing about something and then find out, it’s someone in a team of one working on a greenfield project. Their take may not be at all relevant depending on your specific situation.