Is RSC on Rails actually ready?
Use the official starter and setup docs as your baseline. Production readiness still depends on deploying and sizing the Pro Node renderer, enabling RSC support, and validating your application's bundles, stream, and fallback behavior.
When is Next.js (or TanStack Start) the right call?
Choose Next.js when a separately deployed frontend, reusable APIs, independent team ownership, or its caching, prefetching, Partial Prerendering, and static-delivery ecosystem are product requirements. Choose TanStack Start when you want its full-stack JavaScript model rather than a Rails-owned application.
What does it cost compared with Inertia or Next.js?
React on Rails and Inertia Rails are both MIT. The paid part of this stack is ShakaStack Pro (React on Rails Pro, ShakaPerf and Slack support, $1,800 per year per organization), and only in production at organizations above the small-organization line: under 10 people, $1M revenue and $1M raised stay free, as do charities, schools and hospitals. That subscription buys what Inertia Rails does not have today: React Server Components, streaming SSR with selective hydration, and fragment caching. Next.js is MIT too; its cost is the separate frontend deployment and the second application boundary.