Interesting if a bit long. I normally use Damian Conway's Text::Autoformat for reformatting emails and such in vi. It seems like it would be a useful addition to create a mode for it to handle your commenting style as well so that comment edits are painless. Heck, it may already handle this format and I just don't know.

Update: I just tried it and it works fine as long as you're willing to live without the trailing # on each line. I.e.,

######################################################################
# Hello there, this is a test.
#              And this too is a test.  More testing,
# more testing, more testing ... What a bore!  :-)
#
######################################################################
[download]

is reformatted as

######################################################################
# Hello there, this is a test.  And this too is a test.  More testing,
# more testing, more testing ... What a bore!  :-)
#
######################################################################
[download]