I have both boxes (and actually had most of the material on vinyl for years). The MOB box is really a collecton of sessions by varying leaders covering a period from 1940 until the mid 50s and in many cases linking the session's with Condon is really a marketing ploy on Mosaic's part. i.e there was NO marketing link with Condon when the Jimmy Dorsey "Dixie By Dorsey" came out, although Cutty Cuthsall and Dick Cary were close associates of Condon. Likewise the "Billy Plays Bix" lp and I'm sure the others. The result is that the Condon All Stars box has a unity of approach and a continuity that the Mob Box doesn't.
However....The session that opens the Mob Box (Bud Freeman -with Eddie on guitar) is an essential date. There is some primo Jack Teagarden and Pee Wee Russell on these and they are just great. I've had this on 10" lp, several times on 12" and the sound here is by far the best I've heard and again...this is a great session.
There's a lot to enjoy on both boxes, but when listening to the Mob Box it might be better to take each session as an individual recording, independant of the session preceeding it and following it, both as leader and as to when it was recorded.
I had to have both boxes...but that's me.