Stepper motors are neither economical or appropriate for motion control
when significant force is required as is the case for CNC metalworking.
Servomotors are the proper element. Steppers' only virtue is relative
simplicity, but this is obviated by Geckodrive controllers and the like.

This is simply not true. Steppers produce a lot more torque than you
apparently think, with even small 23 size units producing over 600
oz-in. Coupled with any reasonable leadscrew / ballscrew pitch that
translates into plenty of force for smaller machines. Since smaller
machines also don't have high HP spindles, the stepper drive is well
matched to the cutting rates that the spindle can handle.

For all but the smallest machines, I also believe servos are far
superior. That 600 oz-in is 3 ft-lb, most anyone turns manual handles
harder than that. Exceed that for even a sec and the machine looses
steps and ruins the part.

Now my bias against steppers is based on bitter experience. When the
bandit control died on my knee mill, I had to go to steppers as no
cheap PC control using servos existed at that time. Even after
upgrading to high performance 2000 oz-in steppers I continually lost
steps and ruined parts. I had to make parts at 1/4 speed and watch it
like a hawk.

So, I watched eBay and bought a high dollar control for cheap. Then
put those bandit servos back on with encoders. WHAT A DIFFERENCE!
Don't know why I put up with steppers for two years.

Now today, with EMC2 well developed, it makes no sense to go stepper.
You get a free control with position feedback and a strong user base
for support.

Just my two cents.

Karl