Be careful about the legal side. Whether it's shares or "future profit sharing", you may be offering unregistered securities. The Howey Test (https://consumer.findlaw.com/securities-law/what-is-the-howe...) is what you would typically look at to decided if what you're offering is a security or not.

In short, if you go this route, you should look at not just the business trade-offs but also the legal implications. You can probably get a brief opinion from an attorney for somewhere between $0-$500