How do I decide if I should hire a business manager who expects a salary package much higher than our current employees without creating issues?

I own a specialized industrial equipment manufacturing company which I started 20+ years ago and has done quite well. Our sales and growth have stagnated over the past few years primarily which I think is due to : #1. Being 'home-grown', we have lacked professional marketing/sales and have primarily depended on referrals, online (Google etc.) marketing & a few print ads in trade magazines. #2. Over the past few years I have spent lesser and lesser time at the company with zero efforts towards new marketing channels etc. Recently we were approached by a very talented individual who operates (CEO) a similar but unrelated niche manufacturing company. I believe he could take our company to the next level as he has done at his existing company. Of course no guarantees but I am willing to set aside the considerable cost associated with this endeavor for a year or longer, assuming I see some ROI within a year. Which brings me the to the question above!