How does this compare to standard ABC? More capable, presumably, but a comparison would be useful.

https://en.wikipedia.org/wiki/ABC_notation https://abcnotation.com/

ABC notation is more oriented towards traditional sheet music, with regular note lengths, standard Western tuning and a simple, readable syntax. It isn't meant for playing back music that sounds good to the ear. It's hard to catch the nuances of a real human performance with it, but it works well as a lead sheet for musicians. Its expressive marking are relatively limited and interpreted subjectively.

MTXT focuses on editable recordings of live performances, preserving all of those tiny irregularities that make the music human. It can represent arbitrary timings, subtle expressive variations and even arbitrary tuning systems. MTXT can also capture transitions like crescendos and accelerandos exactly as they happened.