How to organize and tag classical music

[Pastim]

My need for the Group tag was driven, at least in part, by the behaviour of my Control Point (CP), and a tendency to select duplicate tracks when playing a minimserver container at anything other than track level. By defining Groups some of the worst of this can be avoided, since a Group always just contains tracks, not a further breakdown of tags.

I'm committed to linux, which severely restricts my choice of CP (most are hopeless). I believe I have now found one that is very practical, called upplay.

What CPs are others using?