[Donito]

Would you both be working full-time on your startup? If that's the case, which shows a complete investment from both parties, I'd suggest giving it a try. His solid background (e.g. Big Four, IB) shows that he is goal oriented, talented, and will definitely be an asset to complement your technical skills.

Also, consultants have the benefit of having been 'dropped' in many different businesses, and learn about their problems/structures. His potential knowledge of those markets would also prove to be valuable.