What I meant by "feel about" was pretty much what you've responded to but perhaps a bit more. It basically starts with my feeling that in most cases, there really isn't a need for "creating space" or helping a certain part fit in the mix. Before anyone jumps down my throat, please note I said most cases. I've certainly heard mixes that needed EQ help. I recorded some myself. But for me, they've been quite rare. And you went straight to the heart of the matter with a swing big band. Think about it. You've got Benny Goodman's orchestra 30 feet in front of you in an at least decently acoustically prepared space. Do you expect to hear a need to EQ the tenor saxes so Peggy Lee will sit in the mix better? I would expect it to sound (and look) like heaven on earth. And yes, these were outstanding musicians but I don't believe Harry James could attenuate a 700 Hz hole in his trumpet.
In short, if the sound is there live, it should be there in a decent recording.
But perhaps this is more of a problem of tracking single instruments? Or perhaps I overestimate the use of this engineering tool/technique.
As far as bluegrass bands performing live with a single mic, it is mostly because of tradition. But it also adds a bit of showmanship and dynamic to what is normally a very static stage performance. When done well, the fading up and down of the instruments by the movement of the musicians in relation to the mic can sound quite good. And worthy of recording, IMO.
