Evidently you didn't have the pleasure of our company sometime back when one
of our esteemed unfortunate colleagues was working on a 1880's building with
sharp-edged molded-brick laid in butter joints, and had to figure out how to
repoint it after the mortar had turned to moosh and only remained in place
because the joints were so narrow.

I would like to know more about this project. Here in Savannah we have
numerous historical buildings similar to what you are describing, but from
what I've seen they seem to be holding up quite well (mortar joints). The
same type of brick, same type of mortar. Do you by any chance have some
before photos of the building you are referring to? As far as selling eye of
newt instead of snake oil goes, I'm fully convinced that the use of lime
mortar, stucco, or lime wash is beneficial to the longevity of historic
structures until such a time that someone can prove otherwise. All one has to
do is look at the castles of Europe, or the pyramids of Egypt and come to the
conclusion that lime is beneficial. After all we are talking about centuries,
or better yet millennium. I would prefer to rake out 150 year old lime mortar
joints over cement joints any day. Of course you will not be raking out
cement joints, you will cutting them out along with the brick. In modern
construction that is no big deal, but when you are dealing with a historical
structure that is 130-150 years old or older there is a 99.9% chance that you
will not be able to find a source of brick that was used in the construction
of the building. So, why not use soft lime mortar? If you are averaging
between 75-100 years before you must repoint I think that is pretty darn
good. Plus the added benefits of not having to replace original brick. Any
idea if this particular building has ever been repointed before? If not, like
I stated in my previous post I think that 120 years or so of service is
pretty good bang for your buck.

Steve