How do you quantify if your organization needs Enterprise Customer Success?

By definition, Enterprise Customer Success means that you are selling a product that becomes so fundamentally core to a large enterprise's own workflows, processes, policies, etc. that they spend a lot and have very high expectations for ROI. So if you need to quantify or justify with that quantification needing Enterprise CS, I would argue that the customer journey is complex and the customer needs a field guide. That journey is basically the path to value and all the ins and outs of what to do and how to measure doesn't just happen by itself or in a self-serve manner. If it did, it wouldn't be an enterprise-grade solution.

I think that Enterprise Customer Success means different things to different companies. This term Enterprise is used very freely and generally means CS for your larger organisations. But you must first determine for your business size, what is a large organisation to you? And why do you think they need a different level of service? What's the feedback you've been getting or what are the difficulties you've been facing with your current model for these customers? That should tell you everything you need to know.