On first glance his offer seems reasonable. He seems to believe in the potential of your technology as he's happy with equity alone, which is a good sign (provided he can deliver on his promise).

Your decision basically boils down to time. How many people are on your team already? If you spent time doing the BD yourself, what would the opportunity cost be? Could your time be spent better on the product or tech? Do you see him bringing value proportional to his cost? (x% equity)