In the 70's, he released Trance, a wonderful album from a time when, as a friend once stated, "Every album ECM released was a classic." It was a unique fusion of jazz and classical music, with a dash of Kuhn's wry sense of humor. If memory serves, he went on to record a couple of more albums for ECM and then his output seemed to drop off.
I saw him with a trio at the Village Vanguard in New York in the mid-eighties and he put me to sleep. Every once in a while I've come across a CD of his, but they seemed to be standards-based, which struck me as curious because I liked his original compositions so much. I have his ECM CD Remembering Tomorrow, which again seemed a little lifeless to me, but I'm glad he's back with a new one on the label that's released his best work.
If anyone has opinions on the ECM albums he released in the late-seventies, Motility and Non-Fiction, please post a comment.