I think that's the only trumpet concerto he wrote, Ron, a marvellous work I think. I like all of the earlier works of Zimmermann that I've heard, although my favourite piece of his, and in fact I think I would say one of my favourite pieces by anyone, is the much later Intercomunicazione for cello and piano.
It's a marvellous piece--for me much of late Zimmermann is. Hasn't Ian Pace recorded it? If so, would he like to share some thoughts on the work?
Yes, with Friedrich Gauwerky. Absolutely wonderful piece, manages to work some of its more 'constructed'-sounding material into a sometimes nightmarish vision (a little like Kagel in that respect). Bit busy at the moment to type anything at length on it, but will try to do so later (maybe in the Zimmermann thread rather than here).