I can tell you that as a programmer with a music background, lilypond has been a godsend. As programming is my day job, many of my notation projects are long-term things that won't get touched for weeks. I have a backlog of 40-50 piano improvisations I want to notate, plus some pop/jazz originals for which I write various different versions of arrangements / lead sheets, not to mention a collection of altered lead sheets for my jazz group. And much older classical compositions from college, and a full-orchestra film score I did once.
With my git repo, I can see diffs over time, I can "compile" different versions of the scores, and by far and away most important, I have long term backwards compatibility. It was just last month I realized I missed porting an old flute duet from Sibelius to Lilypond, and I could no longer open Sibelius due to my version not running on my hardware anymore. Putting me in the position of having to buy an upgrade just to see it. Luckily I found one exported pdf, and that was enough. Now it's in Lilypond and I'm safe.
With my git repo, I can see diffs over time, I can "compile" different versions of the scores, and by far and away most important, I have long term backwards compatibility. It was just last month I realized I missed porting an old flute duet from Sibelius to Lilypond, and I could no longer open Sibelius due to my version not running on my hardware anymore. Putting me in the position of having to buy an upgrade just to see it. Luckily I found one exported pdf, and that was enough. Now it's in Lilypond and I'm safe.