I was faced with a similar situation about 8 years ago, increasing modeling complexity, more join tables and more attributes to take into account. I did a proto

I was faced with a similar situation about 8 years ago, increasing modeling complexity, more join tables and more attributes to take into account. I did a prototype on Neo4j just to see if it would make things simpler for my case, and it did. Subsequently, I ported the entire data model to Neo4j, as I think the complexity of handling multiple databases is unnecessary if it can be avoided. After taking two products to market using Neo4j as the database, my interest in the technology was such that I now work full-time in the Neo4j development team, so obviously I have a bias (although I did not back when I was in your situation). But I still think the best way for you to make your own mind up here is to create a prototype project. This is usually the best route for any technology choice. You already know how to model your domain in an RDBMS. Make a prototype in Neo4j to get the knowledge you need to make an informed decision.