Just my opinion, but this set bored me, so if you already have a "fair bit of it," that's probably all you need.
Well, let me just say that this set is one of my favorite Selects. It grew on me, and I now consider it a great body of work. There is much here that doesn't come out and slap you in the face, but woos you over time. Very interesting new takes on older material, very mellow and swinging playing.
The Brookmeyer is a favorite of mine too. The guitar (Jim Hall and Jimmy Raney) mixes really nicely with the valve trombone--like Lon said, a mellow sound (but still swinging)