Great idea for a project! I too was a big fan of Amarok, and have been disappointed by music players since having used it.
One thing I haven't seen mentioned, which Amarok, excelled at but other players haven't, was dealing with large (>100gb) collections hosted over a network. Hopefully you'll include this in your testing. As well Amarok allowed you to store metadata in arbitrary databases (which QT had support for) hosted on a network, thus allowing for metadata to be shared by computers for a given account. Quite common nowadays is to use SQLite locally; however SQLite does not support working over a network :-/
One thing I haven't seen mentioned, which Amarok, excelled at but other players haven't, was dealing with large (>100gb) collections hosted over a network. Hopefully you'll include this in your testing. As well Amarok allowed you to store metadata in arbitrary databases (which QT had support for) hosted on a network, thus allowing for metadata to be shared by computers for a given account. Quite common nowadays is to use SQLite locally; however SQLite does not support working over a network :-/
Anyway, kudos and fare-thee-well!