You mean the low end torque issues/stalling?
The motor & controller on the s2 is from the same company that is selling to Keling. I can't get a decent pic of Keling's controller but I'm guessing it's the same. The problem people are having seems to be intermittant. Personally I have stalled the motor twice but it was under extreme conditions. So I haven't personally had these problems.
But, at the same time, I almost never have to be running at the extreme low end speed-wise, where the problem usually seems to pop up. I also got an early version, so the problems may have been created with later revisions of hw or sw.
In theory, if the current NM-200's are still using the same spindle setup then they could be affected by the same problem.