John,
It is a big difference between a Turbo S at full TURBO and a base Turbo in ECO40-60. If I ride at full Turbo, I find I just go faster, but keep spinning in the 80-95 rpm level because it is comfortable. However, with the power output of the base Turbo, I can still get into a pretty low gear when climbing.
My background is that I raced bicycles back in the early 1970s (while in college). I trained to ride a fast cadence and it is comfortable for me to do so. If I ride at too slow a cadence, my body goes from aerobic exercise to anaerobic. This puts stress on muscles in a way that doesn't work well for me (kind of like shoveling snow or lifting too much weight). After a heart attack 16 years ago, I find it can take 24 - 36 hours to recover from even a short amount of anaerobic exercise, while I do fine riding for hours as long as I keep "spinning".
Doug