When I researched this for my MiniMax J/P I found that there was enough concern expressed about the electronics working properly with a VFD that I went with a RPC. Aside from being annoyingly loud the American Rotary model I got has been perfect. They were great to work with. The model they recommended for my 7.5 hp machine has a 20hp idler motor and required a 60A breaker, so that's a consideration if you're light on power.