By "equation editor" you may mean some add-on software designed
to compensate for the inadequacies of word processing
software in this respect. (To be fair, does any word processor
claim excellence on this criterion?) I can't comment on those,
as I've never used any. However, I know that many people have
struggled with the fact that their word processor uses different
systems for displayed equations and in-text mathematics, so that
even on a simple level it is difficult if not impossible to use
identical fonts. That may be folklore; however,
I've never heard of a satisfactory solution to this problem
except not using a word processor to prepare mathematical
documents.
To expand on this: Equation Editor in M$ Word (which is really a "lite"
version of the commercial product MathType) operates on equations (and
even single Greek letters) as GRAPHIC OBJECTS, so that a lengthy paper
with many equations and symbols will be absolutely huge, since it
contains many embedded graphic objects, giving ample opportunity for M$
Word to choke someday and determine that the file is no longer readable
(one of our secretarial staff has empirically estimated that
Pr[failure] approaches 1 as the equation-rich paper gets to be 50 pages
or so). The graphics do not auto-resize when you change the font size,
since they are not text; they are a picture, and must be manually
resized to suit. Bleah!
