I carry the PPS IWB everday. Great gun. I also have a Smith and Wesson M&P Shield 9 that stays in the safe. It feels good. Slightly lighter and thinner but the PPS feels "right" to me.
As far as your two options, I compared the PPS next to the Kahr side by side... THe Walther seemed to fit my hand better. Both are/will be great guns. My vote is for the PPS. Ironically enough I am going to buy a Kahr soon as I have had my PPS a little over a year, and granted I love it, I am due for a change of scenery.