Bun vs Node.js: Why I Stayed on Node for 4 Production Systems (And Where Bun Actually Helps)

I evaluated Bun as a runtime replacement for my Node.js backends across TMS (Express + TypeORM + PostgreSQL, 1M+ records), aiPM (Fastify + BullMQ + Redis), and The Weekend Stores (Fastify + Drizzle ORM). Here's what compatibility actually looks like on a real enterprise stack, where the performance claims hold up, and why I use pnpm instead of bun install.