The step velocity mode was meant to use step mode up to the transition velocity (user set if I recall) then it would change to Velocity mode. So at slow speeds it would act exactly as Multi Step mode does and when wound faster would change to Velocity mode. As said it never worked well.
The controllers I use (CSMIO/IP-A and IP-S) treat the MPG as per normal in Industry, ie x1 x10 x100 and that means each click is exactly the setting you are on. I think that Mach 4 will use that method as well.
Hood