Well, it'll be a cold day in hell before you hear me do a rhumba version of an old foxtrot tune on an arranger out in public (I want to stay working, round here!), but I kind of see your point

Mind you, with SMF's and Markers, you can do some quite similar things, throw transitioning seamlessly into style mode, all holding the same tempo, and yes, if given the time to set things up in advance, I guess most audiences would be hard pressed to tell the difference...

It's cool, for sure, but it doesn't really make MY 'must have' list. Even if I'm NOT doing big band music!