I have an aluminum gantry router using one of my 430 oz/in servo motors belt driven at 2:1 ratio. I am using .2 pitch ball screws and can move my gantry at 200 IPM rapids. Cutting at 60 IPM .5 deep should be fine if you keep the spindle RPM high and you are not trying to do this with a large router bit like 3/4"
I need to do some testing of these 'Cheap servo' motors against my new ones from Poly-sci. My new motors are a bit longer and are 1/2 pound heavier.