Just got a test roll of the Awagami Kozo thin White.
Couple of observations.
The paper is much "harder" than EKT - less soft in the hand, and much harder on a scalpel.
The gamut (profiler 2371 patches) is way smaller than the Epson, particularly in the reds. The outback test image strawberries are about three days past their best. That said, monochromes are looking pretty good.
Transport through the 8400 is painless, the paper seems very compliant with no aggressive curl and without the (Epson) backer shouldn't have any issues with piping.
I started with the Awagami Kozo thin white, as I can get it in 17 & 24" as well as 44". The thin natural is only available (from my supplier) in 44", which was just a touch too expensive to get a roll to test.
I think it will have a place in our range of options, just no poppy fields, post boxes, Arsenal, Liverpool or United, or London Buses.