Thanks to everyone for your suggestions!
Ben: Yes, I do use Frescobaldi; it's definitely my editor-of-choice after trying several different solutions. My favorite thing about Frescobaldi is that it is lightweight... hopefully the long-term plans of adding lots more functionality to Frescobaldi do not make it unwieldy.
Richard: Your video was really impressive. On my first try, however, Denemo was really frustrating. The tooltips took me at good 5-10 minutes to figure out, then every time I tried to connect my midi keyboard, it crashed. Perhaps I'll try again sometime soon. I'm sure that, like LilyPond, it's worth getting over the learning curve.
David: I wish I could help with Frescobaldi development. Perhaps in the summers I will have time to work on learning enough to help.
Nathan: I loved your suggestions, and after trying them this month, found they really helped me. I think I was so slow before because I would compile and check the output every few bars. When I put it all in quickly, then proof, it goes much faster. Thanks!
Ivan: Thanks for your suggestion to use Vim. I've used Vim somewhat and like it for terminal editing. Frescobaldi is definitely my favorite right now, though.
Thanks again everyone!
Sam