Both our kids learned to read music without specifically being taught- they were in group cello lessons in school and the teaching was primarily by ear, but the kids did for some reason get sheet music of the pieces. The group lessons were frustrating, as they did learn faster and were ready to move ahead way before the group. The hand strength required for cello was frustrating for my DS, but he was able to see the benefits of regular practice. Still, after a year both kids switched to individual lessons on woodwinds. Again, both have found it easier than their peers seem to; DD earned first chair in her All-county orchestra at the youngest age eligible to try out. DS is still in the early stages and braces have added some frustrations to his initial progress.

As far as balance, the only issues have been the occasional major conflicts like science olympiad tournaments and all-county on the same weekend kind of stuff; you learn to prioritize and work it out (remarkably, the same kids are usually involved). Overall, it has been a great escape and relaxation tool, particularly for DD, and both enjoy the camaraderie of band, even if the music is not particularly challenging for them.

ETA: forgot to mention that although DD refused formal piano lessons, she has always been able to play her band and orchestra music on the piano, and has taught herself to play fairly well things which she finds interesting enough to work at- usually minecraft music she finds online, or Journey songs😊.

Also, our experience with sight-reading is like that of HK; my DD is very, very good at it. DS is hard to tell yet- he's crafty with his skills