I'm another K10D owner who's been following the K-5 with interest.
I've also been wondering in the back of my mind whether it's just a desire for a new gadget, vs. a way to genuinely improve my photography.
One way I think of it is like this - does the K10D prevent me from getting the shots I want? If so, it's become a technical roadblock that could probably be removed by a newer, better, camera.
While I can't see the K10D preventing people getting awesome landscapes, etc. I had a recent experience where the technical abilities of the K10D stopped me taking photos.
During a recent sight-seeing trip to Washington DC I just had the camera and a slow walkabout lens with me. As the light started to fade, I couldn't get an aperture/ISO combo that resulted in a shutter speed high enough for blur-free photos. The K-5's excellent high ISO performance would have allowed me to continue shooting that little bit longer into the day.
(I realise a tripod or faster lens would have achieved the same goal, but better ISO is more universal as it applies to all lens in all situations).
I've also found myself frustrated when the K10D has failed to find focus in low light.
So for me, I feel an upgrade to the K-5 will allow me to get photos I can't with the K10D.
As an aside, I've been trying to list all the reasons to upgrade (in no particular order):
* Smaller, lighter body - This will probably mean I take my camera with me more often, when the K10D would have otherwise been left at home
* Better high ISO performance - Maybe as much as 4 additional usable stops
* Bigger, better LCD screen for reviewing images
* 100% viewfinder
* Faster AF
* More accurate low-light AF
* More accurate metering (16 vs. 77 segment)
* Higher FPS (7 vs. 3)
* Video - not essential for me, but I'm sure I'll use it occasionally
* Live view - same as video
* Higher maximum shutter speed
* Improved dust removal system
* An additional 6 megapixels of resolution
* Electronic level - could prove useful
* Programable Fx button
* X-sync socket
* Not sure if the shake reduction system is improved?
What would I lose from the K10D?
* Tethering
I think I've done a good enough job of convincing myself I NEED a K-5
Adam