I have not heard any "music station" on AM/HD and being out of market I cannot hear WLGZ except for their webcast which has some issues with cutting off the commercials and covering them with PSA....10 seconds after the commercial has already started.
I have heard WOR in HD and it does sound good...certainly better than any AM analog signal. Of course, the IBOC system does introduce a lot of hash on the sidebands and adds a noticable hiss on the center frequency and reduces am audio bandwidth. Most analog listeners do not notice it.
Those of us with a radio background are driven crazy by it, but most civilians don't even hear it.