Mobley was one of a number of saxophonists in the interim period between Trane's departure and the George Coleman edition with the new rhythm section. And Mobley wasn't with the band that long, it's just that the amount of recorded material gives that impression. IMO, Mobley is coincidental to the overall sound; I think the rhythm section is the key to the change in tenor (no pun intended).
For me the highlight of the Blackhawk sessions is the amazingly high quality of the Wynton Kelly Trio, as they would shortly become.
Miles didn't like Hank, Tony didn't like George, maybe Miles wasn't happy with Sam (but Sam also said he felt constrained), but Everybody Loves Wayne.
As far as Sam and Miles, I think I said this on another thread, it's funny to think that Sam was too "out" when you listen to what Wayne was doing at The Plugged Nickel.
There are hints of something (Milestones), but on the whole Mile's playing with Bird was pretty raw - nowhere near Fats or Diz. In fact judging from his early playing, as a horn player it's remarkable he became as great as the critics said he did.
Q
The Milestones (orig.) session was Miles' first date as a leader (hence Bird on tenor), and it gives a hint of his mature sound (as does some of his playing on the Royal Roost sessions toward the end of his tenure), but don't forget that Miles was very young when he played with Bird, and MUCH less experienced than either Fats or Diz. Still, the lyricism you hear on his Milestones/Half Nelson date and the Royal Roost appearance with Dameron (very different from the Paris date) shows the special lyricism that he'd further develop.
There's plenty of "bebop greatness" on some of Miles' 1953-56 Prestige and Blue Note recordings, IMO.