And as an aside: I would never make vague promises that I don't know I can keep to employees. They're asking you to work for free. They should be clear on that,

And as an aside: I would never make vague promises that I don't know I can keep to employees. They're asking you to work for free. They should be clear on that, and you should get more equity for that (and with the same rights they have). Bad deal.