ease of comprehension-relevant?

[RonButters at AOL.COM]

In a message dated 9/10/02 4:01:41 AM, TheEditor at WORLDWIDEWORDS.ORG writes:

<< It
would have been better if it had led to firm conclusions either way
about the relative ease of comprehension of upper- and lower-case
messages, but that subject is, after all, rather off-topic for this
list. >>

it seems to me that this question is of direct relevance to the question of
how and why this odd rule got started in the first place, so to my mind it
would definitely be worth pursuing within the framework of the semiotics of
contemporary American English