We have an upcoming client project that requires building an interactive community platform with user profiles, instant messaging, and content feeds. Our project manager suggested using the MERN stack so that our engineers only have to deal with JavaScript across the entire technology stack. I am a bit skeptical about using MongoDB for structured relational data, but the speed of prototyping is appealing. Has anyone used MERN for commercial projects with heavy user interaction. What are the key architectural trade-offs.