Originally posted by leekil But the KP doesn't seem so much different in size & weight than the K-3?
The other replies have said most of it, but there's nearly a 100 gram difference between the two (the K-3ii is slightly lighter, so the difference is 80-odd grams), which isn't startling any way you look at it, but any reduction in the load on your neck or back is welcome, no matter how fit you might think you are.
However, that weight reduction is signified by the reduction in the overall appearance of bulkiness, with the KP.
Having said that, the mirror box and the glass pentaprism are always going to make a DSLR heavier than a MILC, all other things being equal. Only the development of a light-weight synthetic material with similar optical properties to glass is going to carve a substantial slice out of a DSLR weight.
Still, we can always hope for an interchangeable OVF/EVF model, too. Imagine having the option of a direct view onto the focussing screen, just like with the LX...