Music has 2 channels, so that feature is of no use. The other feature is cool as it avoids the need t maintain 2 sets of tags, though as far as I understand, it's not widely supported, especially in smartphones
Music absolutely uses more than two channels. Or less. You don't need special "support" either any more than flac, you just decode it and write the bytes to your output buffer.
You don't pick an archival format for the common case, you pick it for all cases. But to answer the question, virtually every film soundtrack for the last 10 years.
