In regard to THE MUSIC MAN's repurposed 5.1 soundtrack: I haven't seen the Blu-ray (I wasn't lucky enough to be offered it to review), but the reworkings of stereo masters to make a surround experience varies from movie to movie. I think GYPSY sounds grand, for example.
I've never thought the sound quality for the soundtrack album for THE MUSIC MAN was ever especially immersive. The sound always seemed kind of clipped and reserved in terms of the orchestrations and resonance, and there never seemed to be enough bass in the mix.
However, I can't wait to hear the lossless soundtrack on the Blu-ray. Perhaps it will have a wider sound though, admittedly, I just think it's one of those tracks that just doesn't measure up to some others from the same era.