So, these DC motors have actually been in service in standard/classical machinery for some time. I think SCM was actually the first, since I can recall seeing it (technically, an "electrospindle") on their top end shaper back in 2012-ish. We use it on our high-end shaper and obviously, the K590. I imagine there is a cost premium for this, since you need more electronics to run an electro-spindle than a regular induction motor, but they are not really new to the industry. I think you will start seeing more and more DC motors in ww'ing applications as time goes on. For example, that new Harvey dust collector or the new Comatic power feeders, which are really nice.
Erik