Skodadriver, thanks for sharing your experience and perspective, as that can sometimes be more practically illuminating that getting lost in specification charts and even long lists of user reviews!
In reading about the K-5, I learned it's predecessor was the K-7, and in reading about the K-7, I learned it's forerunner was the K-20. Just when I think I am about to have some understanding of the numbering system I discover I don't have a clue....
It seems to be known and accepted that the K10D is noisy above iso400, and the K20Ds higher limit on the iso range should be an improvement, but some of its users seem to be even more frustrated about the noise it gets at iso800 and above. Could part of the issue be people adjusting to that early generation of the CMOS sensor? The K20D is weather resistant, but unless it is cheaper than a K10D, I am thinking (-x-x edit x-x-) that a K10D is most likely the next step up from my K110.
People seem to rave about the K-X / K-R's low noise at high isos (and I need to give serious thought to how important to me that could be for some kinds of pictures), but I don't know why their bottom end is only iso 200? Why no 100? I would also have to worry about avoiding getting one in one of those infernal colors, too. I'm not trying to match my camera with my shoes or tie. If I'm not a teenager trying to look "cool," shouldn't a camera be black or silver, or some combination of those two?
Nobody mentioned the K-7. Is it sort of the rough draft of the K-5? On first glance its user reviews remind me of the ones for the K20D -- several people love them, but a few have more of a love-hate relationship with them.
Now I need to look up the K-3 since it has just been mentioned.
Oh, one important question --- when people talk about "autofocus confirmation" is that the same as the little red square I get in the viewfinder of my K110D, when I get a manual lens into focus (usually accompanied by a green blob on the information line at the bottom of the viewfinder)? I've gotten used to using that crutch. If some of the suggested models don't do that, it could be a mark against them for me.