Originally posted by Matthew Saville Firstly: I guess I'm just that impressed with what APS-C is doing at 24 MP, that I feel full-frame 24 MP would be a bit less exciting for most folks. Especially from a landscape photographer's perspective: if I were spending all my time at ISO 100, and my only choices were two 24 MP sensors, I'd be happy with the APS-C option. In other words, if I'm going to spend $2-3K more, (in total for a whole system) ...then it had better offer more than just an extra stop of high ISO performance and slightly higher dynamic range. It needs to throw in some extra resolution on top of that.
Your correct here. I felt the same way. When the Nikon D600 came out I went ahead and spoiled myself for Christmas with a kit and a pair of primes. I shot it for 7 months, but favored my K5 consistently and wasn't overly impressed. It was more than image quality, but the IQ of the D600 wasn't my only problem... it just didn't feel like a Pentax and had a very poor button layout. I ended up getting the D800 and the K3 later that year and I gotta say I'm very happy with my decisions. I would argue that the dynamic range is probably just as good. Comparing the K5/D600 side by side I was able to pull more out of the K5 RAW's. I wish I could go back and put the K3 and D600 side by side...but I don't got a D600 anymore :P
Between the D610, Sony A7, and K3 I would choose the K3 every time. I haven't used the D750 or any Canon so I can't give an opinion there.