The new draft looks good. I think it's just about ready to be submitted
to the IESG.
A few small things:
1) In section 7.1, "if exactly one trailing space is added to one or
more lines of a message which uses the Format=Flowed parameter, the
effect may be a corrupted display or reply" is out of date. Now that a
flowed line is defined as ending with 1*SP rather than SP, it is easier
for mailers that add trailing white space to corrupt the message.
2) non-sp = %01-09 / %0B / %0C / %0E-19 / %21-7F
should be:
non-sp = %01-09 / %0B-%0C / %0E-1F / %21-7F
(19 doesn't come before 20, 1F does.)
3) I would switch the order of 5.1 and 5.2, as a new reader is more
likely to get the concept if they first see how to generate flowed text
and then how to interpret it.
4) Before the insult example in section 5.5, use the fuller explanation
of soft and hard line breaks "(using '*' to indicate a soft line break,
that is, SP CRLF sequence, and '#' to indicate a hard line break, that
is, CRLF)".