I will begin my post with a quote from Mr. Spocko so that if he chooses to, he can engage himself in a debate and then I will expand on what he said with my own insights from using my Kr.
Originally posted by Mr Spocko Of course manual focus avoids the FF issue but you will have to ignore the AF confirm in the VF and beep because that can be "off" Live view uses contrast detect AF so does not suffer from this problem at all If you are happy to use both of those you might be happy with a K-r
As others have mentioned, it really depends on how you plan to use your Kr as to whether or not this will be an issue for you. I acquired my Kr back in April and quickly decided that my (now my wife's) point-n-shoot was a more appropriate tool for indoor "snapshots" at family events and such. However, I do bring the Kr to these events and even have been known to leave it on my lap ready for grabbing those magic candid indoor "portraits" that a DSLR does such a nice job of.
Very early on I switched to a used 50mm f/1.8 for most of these (cheap Vivitar but I love it) . I have since acquired many more manual lenses but for some reason I just have a feel for focusing that one, perhaps because I spent the entire 4th of July with that as my only lens and just got used to it. Anyway, even a newbie like me CAN develop a feel for a manual lens. Also, when I have my Tamron 18-250mm mounted up, I subtly focus using LiveView with the Kr still on my lap. Either with AF or even MF because hitting the "info" button lets you zoom the LCD in real close so you can nail the manual focus right where you want it.
Funny thing is, I developed all these habits before I ever noticed any FF issue with my Kr! I probably had the issue but between me being a newbie and blaming myself and the fact that wielding a big DSLR makes everyone behave differently than wielding a point-n-shoot I never knew it and developed the habits described above.
Since the start of this thread and a couple others this last week, I've done some more specific testing under dim tungsten light and would agree that the FF issue is real. However, whether or not it would impact your photography is really up to your style.
This next statement is not meant to dismiss the problem as non existent or to say that the Kr wouldn't be a better camera without this issue, again, only one user's opinion based on 9 months in the DSLR world... Pretty much nothing you purchase from your car to your house to your computer to your camera will be devoid of known issues or weaknesses. You have to weigh the value proposition against the strengths and weakness of each product you consider and make your selection. For me, the choice was Kr, and since I don't try to autofocus through the viewfinder in the house, that FF weakness is not an issue for me.
I suppose I could get all worked up that the issue even exists, but then I'd have to get all upset that my 6-speed transmission in my Mustang is stubborn to shift in below freezing weather... but there again, I tend not to race through the gears setting 0-60 speed records in the snow anyway and everything else in the 400hp 4-passenger category was significantly more money.