It seems that I can sum up everything that I know about spinning as:
- Spinning faster makes spinning fine much easier.
- Spinning fine makes spinning faster much easier.
- Spinning faster results in better warp.
With the correct bobbin, AA's #0 flier will spin worsted using Irish / German Tension at the wool's spin count.
This is a leap that I did not expect.
It seems that some of the advantage of the DD/DRS system was that it simply allowed me to spin faster. On the other hand, it does help spin the grist that I want instead of just spinning at the spin count.