I love Milt Jackson's music, he's one of my favorites in all of jazz. John Lewis: he's pretty boring in the context of MJQ (IMHO), but I do like a few of his solo efforts on Atlantic (for example, "The Golden Striker") and RCA. I would blame the MJQ dynamic more on the success of the format: the tuxes, the composed demeanor, the demure performances. Of course they could really swing, but when they did, it was still really polite. But it was marketable, which I do not criticize.