Re Japan, I think "bloated" is closer to my thinking than "dense". (Though I prefer "unfocused" or "diffuse", and probably like it better than Scott.) I feel like there is a lot of wandering when nothing is happening, like the group wasn't caught on its best day(s).
Re Seattle, I also think it's a mixed bag. The opening track is magnificent - the raucous saxophone choir on top of the burning Tyner-Garrison-Jones rhythm section is thrilling. A great glimpse at a path-not-taken. Some of the longer performances I'm less crazy about.
The "Creation" track that JSngry posted - from the Half Note, 1965 - is one of the best Classic Quartet tracks out there, full stop.
I'm in this camp too. I don't mind when he's playing, but would trade that in a heartbeat for more Coltrane playing. And I find Pharoah's playing with Don Cherry around the same time to be more satisfying, probably because Don provides more contrast.
So I've agreed with you thus far, Scott, but this is a road too far.
When I listen to SUN SHIP or FIRST MEDITATIONS, I hear a rhythm section that's 100% engaged and committed to making very radical music. If they're uncomfortable, I don't hear it. I'm not sure if Elvin and McCoy would have hung around if Coltrane had kept exploring in the quartet format, but it's not inconceivable.