I HAVE A SOLID ANSWER! This is based on my question/response with Nuno Tavares (Automated Marketer - check him out): "The Pass-Through model is the BEST long-term approach: Charge your MRR for the platform, your expertise, and your service layer. Then pass usage costs (Phone, SMS, Email, AI) through to the client at cost or with a small markup. Bundling everything into one flat MRR price sounds cleaner to sell, BUT it's a hidden risk: The moment a client's usage spikes, you're either eating the loss or having an awkward repricing conversation neither of you wanted. Pass-through keeps your margins consistent no matter what they use, and you can still pitch "less hassle" honestly, because the simplicity you're offering is that they don't have to manage any of it. Beyond the billing model itself, the Bigger Principle is this: Your ability to grow depends on keeping your systems simple, consistent, and repeatable. Pass-through billing does exactly that; it scales with you rather than working against you."