It's a little difficult to describe, but with larger speakers, the entire "scene" is a bit harder to take in, and I can just instinctively feel that the smaller speaker is "correct" for the room. Everything is marginally smaller but seems better organized and easier to understand.
I also want to add, concerning the Duettos, that in addition to their dynamics, they are said to have excellent speed and timing, which I find important for jazz in particular.