https://www.mikemuizebelt.nl/pdf/K1_markii_iso_steps_100-102400.jpg
(Composite test picture)
https://www.mikemuizebelt.nl/pdf/K1_markii_iso_steps_100-102400_PSR_ON.jpg
(Warning: Large file in ~25MB each)
From my prolonged experience with the K-1, it seems that the high ISO performance improvement of the Mark II is only subtle at ISO 3200 and above. The handheld PSR could give higher resolution, though, when it works. However, noise will not be improved anyway in the PSR mode.