I agree! Mulligan's pairings with Paul Desmond and with Hodges are also excellent. There's also a marvelous session with saxophone stars called The Gerry Mulligan Songbook. But the ultimates for me are the 1952-53 Quartet, the 1956 Sextet and the Concert Jazz Band, which you've already got, Bev. (Don't know the content of the Mosaic, so you may have more than I realise.)
Ah,yes! Forgot that one. And the earliest Mulligan-led session I really like is the Dektette of 1951 with "Four Mothers" etc.