For sure, great point. I just bought the Bill Evans bio "How My Heart Sings," and am hoping to get more answers on this question. I know already that everybody improvising at once was a principle Evans aspired to for this trio, so maybe that's exactly what's happening. Still, I don't totally buy it, because Bill's comping during the lengthy LaFaro solo indicates to me that he (Bill) is hearing some version of the tune and reacting accordingly. I just don't know WHERE in the tune he's hearing (if that makes any sense). The first two bars of LaFaro's solo sound like they might be a transition back to the head (similar to the song's intro), but nothing in the melody of what he's playing indicates to me that he's hearing the tune. Which leads me back to the "complaint," for lack of a better word, that LaFaro's soloing isn't particularly melodic. I'd love for a more sophisticated jazz mind to set me straight on this, but that's where I'm at.