Originally posted by monochrome IIRC, way back in 2008 we debated at length the merits of the KX (
vis. my Avatar) versus the PZ-1P for the crown as "Best Pentax Camera Ever." I believe our joint decision, given the utility of the "A" contacts, was to own both.
What I like about the KX, which I still own, along with a third film body, the Ricoh XR-2s (I guess that I qualifies now as pentax TOO!) is that from a control & viewfinder point of view the KX and XR-2s are identical, so when I shot a lot of film switching bodies was wholly transparent.
the reason I kept the KX after getting a PZ-1 was that the KX did not need batteries for anything other than the light meter, and I have a hand held seconic reflected light meter if the batteries ever fail. It was a total loss of power backup.
they are both good, the KX is not so much built like a brick, it simply is a brick. The PZ-1 is a good demonstration of the quality of plastics pentax had on their upper end bodies. Mine shows very little wear at all.
a few thing to consider, although , for the KX, while it is a fine body, the mechanically timed shutter is somewhat limited in speed increments, compared to the 1/3 stops possible on the PZ-1. I will leave out the higher shutter speeds, but that is also a possible benefit of the PZ-1, but higher sync speed may be of some interest, when shooting wildlife with a flash. The KX is a 1/60, the PZ-1 is 1/250 that is 2 full stops more for use in terms of fill flash and exposure control and well worth it. ALso note that the KX is prone to loss of the top of the image in the viewfinder when using long lenses, due to the limitations of physical size of the mirror and the very parallel light path when using some tele's. My vivitar 400/5.6 has a very recessed rear element (it is so deep I can't see it down the lens barrel), and shows the mirror limitation quite well.
Although not an issue with the likely intended use of a 600mm lens the KX has a cloth shutter and cannot be used with Infra red film as it can fog.