Originally posted by Egg Salad Oh, I wasn't aware AF points on Nikon bodies aren't spread wider.
I'm sure I'd love the D850, but as I said, cost is an issue. The reason why I included both Nikons is that they're available used and hence cheaper than the K-1. Otherwise they are way out of my scope.
I expected someone to mention the KP. I just don't like its design. I know that if I were to buy the KP I'd always feel like I should have just gotten the K-1.
I didn't mention that I don't need FF, but I realllly want it.
Let me rephrase my question: what would I gain getting the Nikon D750/D8X0 over the K-1 apart from AF capability and lens accessability?
The short answer would be that Nikon or Canon can offer a much more refined system. The 810 is a better camera in many ways. Its also over $1000 more expensive and if you don't need all those "other ways" its money wasted. The D750 is a good camera but its 24MP and aside from its AF its simply not as good as the K1. But Nikon has a better flash ecosystem, better assortment of Nikon and third party lenses, better support in software (Photoshop for example), much more support in terms of books, advice, websites, software. Nikon has better resale generally as well; there are more buyers. Nikon and Canon between them have a good 80% or more of the FF market. A niche player like Pentax will never have the wide range of after market options available.
However consider that comparing the K1 to a D750 or D810 simply repeats the mistakes of just about every forum advice. IMHO you would be far better asking yourself if the Pentax K1 matches your needs first. If it does, buy it, its money well spent. If it doesn't meet your needs it won't matter how much you save. For most people a K1 with the 15-30, 24-70 and 70-200 handle just about anything you'd encounter. If you want the really long reach there is the 150-450. Primes are very good particularly the 31mm, 43, 77 and the 35 and 50 aren't that bad either. If you want a sports camera with excellent tracking and high speed frame rate with big buffer you're in the wrong place. If money is no object and you want a camera for sports or to capture fast moving objects buy a Sony A9 - there isn't anything better, no manufacturers in the same ball park much less the same time zone.