I really don’t think you can gauge an engine builder by volume.
Dave, the KT100 user formula has been well sorted out on these forums (EKN Classic). Once you have those numbers you’ll need little or no support except for overhaul which can be done by any competent shop that services the KT100. It’s less political than you might think.
FAA certified jet engine and aircraft technician,
Nicholson Speedway class champion 2001,
Yamaha KT100 Service Center,
41 years karting experience