RJS replace_html MADNESS!!

I'm listing comments within a div, id="comments". Whenever a new
comment is added, the list is supposed to update with all of the
comments for a given element.

*The problem is* that the div updates with the comment I've entered
followed by all of the comments that were already listed, _except_ for
the first one. So if I enter a new comment I'll get the list of
comments which were already attached to the element, followed by the
comment I've entered, followed by the list of comments again with the
exception of the very first comment in this list. Argh!

This is an intermittent error, but I'm not doing anything funky with
sessions or caching or anything, really and truly.

Very, very strange. It _seems_ as if I've got the correct code that
should do this properly:

Relevant controller code: