General Manager Compensation Benchmarks?

I'm negotiating a new employment contract with a key employee at the company I'm buying who is largely acting as the general manager. The owner only goes in once a week for a few hours and still manages the bank accounts and P&L, but this employee is the primary customer contact, manages the other employees, and keeps the trains running day to day. He's historically had a profit share of 5%, with the opportunity to continue vesting up to 10%. This feels high to me, especially as we continue to grow the business, but definitely want to keep him motivated as well. Would love to hear what others have seen for similar key execs.