Your first presumption that we are all up to the K5 is not quite right. I'm still shooting with the K7 and I do like what it gives me but I'm ready to upgrade and look forward to the improvements that the K3 are going to provide.
My reasons for upgrading;
1. improved resolution, with the new AA filter simulator and the ability to turn it off.
I was considering the K5IIs, this gives me the best of both with and without the AA filter.
2. improved auto focus, hopefully this is translated to low light auto focus.
the K7 sometimes has some focus issues in low light
3. 18-135 kit, this will give me 90% of photo shooting, small kit to carry on my motor cycle.
I started carrying a MFT camera in my saddle bag instead of extra luggage to carry my K7 plus lenses.
4. Because I can afford it now! (and my wife said I can
)
Les