The key thing, Richard, I agree, there are some things that just sound better in a specific key. I have persuaded M'colleagues to jump one song from C to D cos I was struggling in C at the lower end of my range, I do sing another song in C but an octave higher, it suits that song but not the former, it it isn't really about range more about comfort. Incidentally, we have just added a song to our rep. in Bb and it sounds like Brass band music at the Miners welfare, quirky, it stays in! As to accompaniment, I had a bunch of musicians join in with me once and then afterwards told me I was singing the wrong tune!