And I have explained the likely reason for your experience. But as long as you make such sweeping statements like "Regulation is rarely if ever needed in motor control" and "Many of the stepper motor manuf. also do not recommend SMPS for their products" which are seriously flawed as are so many generalisations of that scope but they also are not substitutes for actual technical detail and content. They are anecdotal comments which may or may not be correct but without the detail it is a guessing exercise for the rest of us. Is this a forum for you to express your opinions or for the exchange of accurate technical information? I guess that is my point.A bit more "Chaff" !
My response was from experience purely from the reliability issue, regarding SMPS. There is no disputing they will not work, just not the best choice IMO..
This was from implementing motors of all stripes and sizes.
Regulation is rarely if ever needed in motor control, even servo's. As the Electronic Design paper shows.
Many of the stepper motor manuf. also do not recommend SMPS for their products.