Well, we've been saying it all along about the 80s but I suppose human nature being what it is, the difference has to be witnessed. Besides the bass, the biggest difference I can hear with the 80s is in the vocals. They are velvety, effortless and full of nuances. They are also appropriately forward compared with the "in your face" 22s and too laid back 60s. The differences in imaging and soundstage are more subtle between the 60s and the 80s but they are definitely there given the right track.
I'm surprised that you found the 400 packed more punch than the 350. There was no comparison in my 4,000 cubic foot space. The 400 was, to put it simply, wimpy compared to the 350.
