DRS controlled spinning requires spinning techniques that are not taught in modern spinning classes. And, if you are limited to the techniques taught in modern spinning classes, you will have poor results with DRS controlled equipment. For example, "long draw" spinning does not work. At this time, DRS gear would not be my first choice for spinning woolen yarn. On the other hand, one reason for spinning woolen is that spinning woolen can be fast, but DRS allows me to spin worsted much faster than most flier wheels can spin woolen.
Henry Clems says the pages on DRS in AA have caused him a lot of problems. People read AA, and ask Henry for a DRS wheel, then they can't produce the yarn that they want, and they make him take the wheel back.
Thus, we have the chicken and egg problem. Spinning classes do not teach the techniques because nobody has the equipment. And, nobody has the equipment because there was no class on how to use it. There is also the problem that not many wheel mechanics understand the equipment and can find those not obvious mechanical issues.
However, this does not absolve the high status, expert spinners. If they were really interested in moving the craft to finer, and faster, worsted spinning, they would talk about DRS and tell beginning spinners about the equipment and the additional required skills.
A gang of flier whorls of slightly different diameters (steps of 1/32") allows changing inserted twist by simply moving the drive band. Thus, inserted twist can be held relatively constant as the effective diameter of the bobbin changes as single is wound on.
I intend to make a full set of these so I can spin any grist (twist) on bobbins with any effective diameter. And, now I intend to start making bigger bobbins. I did not need bigger bobbins when I was winding off frequently to prevent the effective diameter of the bobbin from changing.
Now, I can spin a full hank of a medium single without winding off.