Live in Seattle is definitely improved. I haven't spun Concert in Japan yet and done the comparison. Dynamics are a bit improved on Seattle, the most improved is the clarity and tonal balance imo.
Edit to add: Did a few comparisons. The Seattle is most improved of all the titles in my opinion. Concert in Japan is improved as well, there seems more body to the instruments. It's hard to describe the overall improvements, I'd say that the new discs are a bit more forward, but instrumental images are more solidly presented. In most the bass is improved, seeming to have more presence and depth.