Certainly some interesting stuff, some of which is available on CD others not. I know the Concerto for String Quartet and Orchestra well, and its among my favourite Diamond scores.
Diamond is certainly badly in need of a full recorded symphonic cycle, its actually a disgrace that not all his symphonies are available on CD. I'm afraid Naxos don't seem to be bothered with completing cycles these days and keep churning out far too much 10th rate music by complete non-entities in their American music series.
Absolutely agree with you!