Interesting points, Laundramatt; warm then hot = a kind of early profile wash. And yet if one wanted to, one could rinse in the second tub instead of the sink.
I was thinking the standard routine with (single-tub) wringers was:
1) Agitated wash, then empty the tub while wringing out, and put the load(s) on a countertop.
2) Refill tub with clean water.
3) Agitated rinse, then wring out.
4) Repeat (2) and (3) again if needed. Hang clothes on line.
5) If multiple loads, one could save the final rinse water and add detergent for re-use as wash water for the next load.
So the Dexter Difference would be, you could put the load(s) directly through the wringer and into the 2nd tub for rinse, and then if an additional rinse was needed, empty & refill the first tub. The main time savings would be in not having to delay one operation while emptying & refilling a tub, which saves a decent amount of time at each cycle. Or you could do multiple loads by saving the rinse water from the first load and using it as wash water for the next, reversing the direction of throughput from left-to-right, to right-to-left.
Question is, were the agitators in both tubs identical in dimensions, speed, and arc?
All this about rinsing in the sink is intriguing because it seems that would take enough effort (stirring it all around with a broom-handle or whatnot) that people would start figuring out ways to mechanize the process by doing it in the wash tub.