After further thought it occurred to me a method to get some hard numbers on this issue.

I secured a small tape measure around the circumference of the handle and made a more sharp witness mark on the throttle. I could then see the below (with apologies to metric members as I know these fractions must look ridiculous...but that's how the tape measures here are printed. In the end what matters are not the numbers in absolute terms but in relative differences)

Total movement of throttle 33/64"

Point at which traction starts 1/8"

Speed virtually the same from 1/8" to 1/4"

From 1/4" to 21/64" speed increases just a bit

Somewhere in between 21/64 and 11/32" abrupt speed increase.

In other words if there is any ramp from slow to mid range speed it occurs within a 1/64" (.016") range of throttle motion...an impossibly small amount of movement to control.

Then did some speed tests with 30' tape on floor and stopwatch. It takes 58 seconds to run 30 feet at the highest range of the slow speed ( in other words with throttle just below the critical abrupt speed change). It takes 12 seconds to run 30 feet at the lowest range of the mid speed ( i.e. just above the abrupt speed change )

So, at the abrupt speed change, speed is increasing by a factor of 4.8 !

In other words,.016" turn of the throttle results in a speed change from approximately 30 feet per minute to 150 feet per minute.

And that's with a controlled test. In normal operations one isn't going to be so careful with the throttle such that the speed changes will be even more abrupt.....20 feet per minute to 200 feet per minute could easily happen..a 10 fold speed increase with in less than 1/8" of throttle movement range is likely.