Well, I'll weigh in since I upgraded from K10 to Kx. My first and last word (quoted from someone else here on the forums) on that transition is - everyone will tell you that the K10 is twice the camera that the Kx is. That may be true. But I get about
four times as many fantastic pictures out of the Kx....and isn't that what we're here to do? Get great shots?
So here's my answers, subject entirely to my own subjective experience:
Yes, the Kx is so much lighter than the K10 there's no comparison. The K10 used to actually give me a neck ache even with a prime on it. The Kx I hardly notice I have on, and with a DA Limited lens on it it's laughably light
I feel like I can have it with me all the time - something the K10 with its weight and bulk could never give me.
-AF speed, especially when taking candid portraits
YES ABSOLUTELY. I missed so many shots with the K10 because of slow autofocus issues. Never happens anymore with the Kx.
-High ISO IQ
YOU HAVE NO IDEA - you'll be blown away. I hated to shoot at ISO 800 on my K10, on the Kx I shoot at 3200 or 6400 without blinking an eye and jump to 128,000 if I really must have the shot, knowing I'll still like what I get.
-dynamic range or overall IQ
YK, I have less highlight clipping with the Kx than I did with the K10. I know that that's not supposed to be the way it is, but that's been my experience. Add to that the 99% accurate auto white balance and I'm almost never in the position of salvaging my photos as I did with the K10 on more than one occasion.
-Better out of the box jpegs
Yes, definitely. It's not a huge difference, but it's a noticeable one. Even if all you got was improved white balance in your JPEGs, that's huge
Things I may miss on the K10D:
-The top display. Are the controls on the K7 harder to use?
Reports really vary on this one. I got used to checking the back LCD for the 'top display' information in about a week. I don't even think twice about not having the top display anymore - all the information is still right there, just in a slightly different place. On a similar topic, the switch from 2 edials to 1 didn't even phase me - I used my right index finger on the front edial, now I use my right index finger to hit the button to switch from "front edial" functions to rear edial ones. The kinesthetic experience is different, but the functionality is not. There are a few functions missing from the Kx, but the missing front edial isn't the issue.
-better sealed body. (I do feel okay taking the K10D out in light rain with my cheap A 50mm f1.7 lens. Maybe I will need to be more cautious about using the Kx in light rain or on the beach)
I live in rainy Seattle, so you'd think having a sealed camera would matter to me more than it does :P I never had weather sealed lenses, so I never let my K10 get more than slightly damp. I take the Kx out in the rain and just make sure to keep it under my jacket till I want the shot, or with a ziplock bag over it with just the lens area open. If I was a real foul weather shooter, obviously these strategies wouldn't work. But I'm not interested in being out in the rain when it's pouring, so my camera doesn't need to be that sealed
Do I wish the Kx was weather sealed? Sure. It would be some peace of mind. But for the drop in price and weight it's a no-brainer for me.
Everything I was in the habit of doing on my K10 I do on my Kx. The couple of specialized functions available on the K10 that are missing from the Kx I didn't happen to use - so that worked great for me
The Kx is so much more than an entry level DSLR, it really should be given credit for its capabilities and not detracted simply because of who it's being marketed towards.
I almost never miss a shot I want with the Kx. The K10 couldn't give me that. At what point do you say which is the better camera?