Ask HN: How to balance Equity when the Investor is also a Client?

Dear All,

I've seen several examples of startups where investors exchange funds for equity, but what about when the investor is also a client for the new business? You could just keep things separated, I know, but any other ideas to streamline the relationship?

Would it be reasonable exchanging funds for services (instead of equity) in a SaaS scenario where the new service will reduce investor/client's existing operational cost?

Many thanks for any insight.