Kudos on making a slick looking product. I'd say that if your UI was less like GMail, I'd consider using it. If it was just that, a UI for any web mail from any domain, like a Mail.app for the web, I'd definitely pay for it.

And to anyone who says they use Gmail for Security: They're an advertising company who openly mines and sells your personal data. Exactly how is that safe?

Keep on working man. Doing good.