I've always liked the two Montreux albums that came out on Arista-Freedom. He seemed to be sort of beginning to straddle both sides of the fence on those and during that period (1975-1976). Later in the decade, he seemed to really head into the changes period you describe, and the Shepp of, say, 1978 was definety something different than the Shepp of the first half of the 70's. Some of that was not plainly in view at that time because a lot of his titles recorded during the late 70's were on the Japanese Denon label, which was not readily available/affordable in the USA if I recall correctly. And he had a LOT of albums released 1975-1980 (the Freedom's, the Horo's, the Denon's, and a lot of one-offs on other smallish labels), so it was hard to keep up in near-real time, even with access to Third Street Jazz.