Factory SX3
I have a factory SX3 that runs steppers.
On a machine this size they are MORE THAN ADEQUATE.
I have reduced the maximum feed rates from 100 IPM on X and Y and 75 on Z to about 60% of that because doing fine intricate work, and a lot of it in a semi-manual mode, the speeds are more than the brain and hands can handle without crashing into things on rapid. If you want to run it fully fast and automatically it will do it. Servo motors would be a complex, expensive overkill. Most small work is done at low feed rates, because you can't push small cutters too fast. THEY BEND even when you don't push them. Repeatability better than 0.001" all axis with a bit of care. I am 100% happy with my 4 axis lot. The only time you would need really fast rapids, is drilling zillions of holes, and without a tool changer, you would not want to do too many.
Cheers.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.