"I doubt either firm were the first to use a variable-DC drive, W-L or otherwise."
The W-L drive system, at least for hoists and elevators, dates back to the turn of the past century, pre-1900.
Which is actually rather interesting as the concepts of "automatic control", now called "control systems theory", would not be developed for another half-century.
Never the less, the W-L variable speed drive did indeed work, and work well, and many are still in operation.
Many of us will remember the so-called "elevator operators" (also called "key operators", as they were in possession of the "control key") which used a "control key" to manually effectuate the equivalent of a "four quadrant" drive system, with the human within the control loop.
In this way, "motoring forward" (i.e., UP), "braking forward" (i.e., slowing to a pleasant stop, while traveling UP), "motoring reverse" (i.e., DOWN) and "braking down" (i.e., slowing to a pleasant stop, while traveling DOWN), could be implemented by incorporating the human into the control loop.
Post-WW-II, we would learn how to replace the human operator with a primitive PLCC, and to obtain the same or superior performance.
Today's VFDs can, of course, do the same job, without the human operator.
Funny, "software glitches" were unheard of in the pre-War, human-assisted systems, whereas such glitches are well-known in today's human-less systems.
