There are two things I have observed that indicate that the K-1 II has has a successful launch in Japan - not stellar like the D850 or recent A7 cameras, but solid nonetheless.
Firstly, the position of all K-1 series cameras on kakaku.com has improved. (This is a price comparison site for online sellers)
- For several months the K-1 has been between 60th and 80th in ILC cameras.
- After the release, the K-1 price dropped and it went up to around 30th, even going above the KP, which has been the top Pentax almost constantly since it's release.
- Today, the K-1 II is at 45th, the K-1 at 55th, the K-1 silver at 118th, and the K-1 II lens kit at 121st. Given that K-1 sales are split across four kits now, that performance is not bad at all. The KP is back at 25th now, so still the top seller.
- You can see where the K-1 sits against other full frame DSLR kits at this link
http://kakaku.com/camera/digital-slr-camera/itemlist.aspx?pdf_ma=14,58,251&pdf_Spec113=1 Hope the link works.
Secondly, Ricoh announced that the upgrade service would be delayed for some customers on May 31. The reason they gave was "we have received applications that far exceeded our initial expectation". So it looks like the upgrade service is popular too.
I think that Japanese customers are much more likely see the benefit of the accelerator because they tend to judge based on printed output. There are a number of influential print magazines that run reviews of cameras. What overseas websites think about pixel level detail won't bother them much.