I agree with the idea that the best way to really experience an improvising group is to hear them on multiple occasions in a relatively short time span. This allows you to hear the growth and evolution of the music, as well as get a sense of some of the other variables like the mood of the players, the venue, the weather, whatever. Similar thoughts have been championed by Ken Vandermark.
The Vandermark 5 recorded every note of a 5 night stay at the Polish club Alchemia in 2004. The whole week of music was released as a 12 CD box entitled Alchemia. It is very interesting to hear every note the band played that week, and there is the added angle that some of the tunes that eventually ended up on The Color of Memory were first introduced on the tour that produced Alchemia. You can really hear the interpretations develop.
Dave Douglas is taking a slightly different approach to offering an all encompassing take on the state of his band. He is recording every active tune in the quintet’s repertoire over the course of a week at the Jazz Standard in New York, and making the whole week available as download’s from his web store. The extra interest here comes from these being Douglas’ first recordings on cornet.