I play classical piano (grade 7) and guitar (grade 8), Canadian if that makes any difference in what the grades mean. I don't think there's any direct benefit between cubing and music, but I do think there's a nice freeing of many mental blocks.
For example, after learning full CFOP and it's initially overwhelming alg lists and so on, I'm no longer overwhelmed by any "lists" of things to learn in music. I think like everyone else who learned full OLL, I was like "57???". But now that I know them it doesn't feel like all that many. This resulted in much more focus and less procrastination when practicing music theory and technique.
Also, now that I've learned the importance of slowing down and looking ahead in cubing for improvement, I got better at sight reading and memorizing music by going as slow as I needed to make sure my eyes were always decently far ahead of my hands. It's not some unique concept, but I used to just stare at my hands and learn the finger patterns visually before I started cubing, which was of course terrible.