[CW] CW Speed Limit ???

[Steve-W0OOW]

The text below was sent to bandwidth at arrl.org.  There were a few individuals
that tried to answer my questions, but all in all the ARRL did not nor has
it yet addressed this issue as far as I have seen, nor has my question been
answered.
... read on - my 2 cents
Steve W0OOW
CW - It's still magic !

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What values were used to calculate the data behind this ARRL statement?

"200 Hz is intended to be the narrowest bandwidth to permit Morse telegraphy
at all speeds that human operators can decode. The necessary bandwidth
depends on speed and whether the circuit is fading or non-fading. An
analysis by ARRL in the 1980s showed that 150 Hz is adequate and is based on
rise and fall times of 5 ms. A bandwidth of 200 Hz will permit data modes
such as PSK31 as well."

The reason I ask is that according to the ARRL Handbook of 1987 p9-9, a
value of K = 3 is used to non-fading circuits, and a value of K = 5 is to be
used to fading circuits.

>From what I get, there is a speed limit imposed on an operator that is far
below a speed that many hams currently use. That of course is allowing for
fading/QSB which we all know rather too well.

"... Morse telegraphy at all speeds that human operators can decode."  Huh?

What value of K was used to make the above statement?

Thank you,
Steve W0OOW