Comparison
Comparison of several music editing I know of. Of those, there are two I use (or used) quite regularly: NoteWorthy Composer 1.75 and Lilypond.
I won't talk about the graphical interface, since MiXuP won't have any. Suffice to say that I liked it because it had well-defined keyboard shortcuts that allowed quite speedy music input.
I won't mention its Windows-only policy, it's their choice. That's one reason I don't use it anymore, although it works perfectly with Wine. The other reasons are its weaknesses (see below).
Strengths:
- cool midi-oriented stuff
- staff merging
Weaknesses:
- not really customizable
- no hairpins (AFAIK fixed in version 2, but I did not buy it)
Nowadays I use Lilypond (the latest SVN version, 2.13.something)
Strengths:
- simple but powerful syntax
- very customizable (programmable and extensible)
- file inclusion (=> modular)
Weaknesses:
- very dumb midi support
- no namespace
- parsing and evaluating are not separate phases; hence weak programming value: in my experience if you modify a value you need to re-parse (e.g. using file inclusion) anything that uses it
All in all, it could do quite a powerful back-end to MiXuP.
Very powerful. Very illegible. Not for the faint of the heart. Not to be written by humans.
One of the possible back-ends to MiXuP, although it requires a lot of tuning and a lot of math.
MusixTeX's frontend. I don't use it, its syntax looks quite unintuitive (but maybe I'm too well set in Lilypond's ways).
AFAICS its notation is too print-oriented, not exactly musical as Lilypond's.
For example, "as a" prints an A# followed by an A (interpreted as a repeated A# by any musician) but Lilypond needs to input twice "ais" to print the same thing, otherwise a becare would be printed on the second A. I prefer that solution, which looks less brittle in the face of transposition etc.
In other words, each note should not depend on the context; only the printing stage should make such distinctions as how/when to print alterations. It allows better modularity.
Never used. Graphical interface. Should be quite powerful since I know colleges that use it to teach music engraving.
I don't like them. Difficult keyboard mappings, and not very customizable (although I confess not to have tried very hard).
Please prove me wrong.