I used to use the SmoothStepper. I've lost count of how many times a change was made in Mach3 that required new firmware and/or a new plug-in for the SmoothStepper to keep things working properly, but those updates always came fairly promptly, and bug reports were always dealt with in a timely manner. What are the chances a low-cost, no-name Chinese motion controller will get updated often enough to keep it working reilably? How are they going to respond to bug reports, if at all? Personally, I would not waste the money. Spend a little more and get something with a proven track record, like the SmoothStepper.
Regards,
Ray L.