The honeymoon continues. I love the camera and the lenses are performing well. I would NEVER go back to a camera without at least a tilting LCD screen. My used 35, 75 and 120 lenses didn't come with lens hoods so last night I made some from Edmund Scientific Flocking paper. Handy and they stuff back into the bag easily. Today I shot several images with very strong lighting just outside the frame and did not see any problems with flare (which I had seen previously with the 120 which surprised me as the front element is quite recessed). Anyway, problem fixed.
I took some images today with the 200 mm. lens at 1/6 second, some with the 2 second self timer, then later with the 12 second - the latter are sharp, the former definitely soft - so I need 12 seconds on the self timer for both the 200 and 300 mm. lenses - so now I know.
Several times today, rather than using live view magnified focus, move the magnified image to the extreme corner (slow), I simply turned live view off and checked focus with the view finder - turned out to work very well (I was focus blending so needed to find the near focus point which happened to be at the edges). This speaks well to the quality of the viewfinder.
When the Sony A7r came out, there were concerns for image sharpness in a vertical format because of shutter shake - although I haven't done any formal testing, lots of images shot vertically have not shown any concerns on the Pentax 645z.
I've been doing a lot of lens swapping, guessing incorrectly on the focal length I needed. It's possible that zooms would have avoided this but my feeling is only to a modest degree and I'm happier to accept the quality of the fixed lenses. This is a bit of a surprise to me - I hadn't thought I'd be as comfortable without my zooms, but so far it's been a non-issue.
Both the 25 and 35 mm. lenses have some barrel distortion, but auto correction with the 25 and manual with the 35 has not been a problem.
I know I have said it before, but I love how robust the files are. I can correct for barrel distortion, rotate the image, fix horizontal and vertical perspective and rotate the image, all on top of focus blending and followed by Akvis Enhancer without the image falling apart and still able to make a tack sharp 30X40 print.
That's all that I ever hoped for and more.
Does the Pentax do anything that smaller cheaper cameras can't do - no - it's simply down to print size. If you don't routinely go above 13X19, there are many cameras that would suit better and be more versatile.
Even if the Nikon 810 came with a complete set of Zeiss Otis lenses (not that I could afford them, my Pentax lenses cost between $200 - $1000 exc. for the 25 mm. so that's 5X$4500 less for a set of lenses - that's a lot more than I paid for the Pentax and 25 mm. lens combined. And to not have a tilting LCD, and to have to put up with stop down live view focusing - NO WAY.