I like the KS-1 and am looking forward to an opportunity to see it up close. I can see that some of the funkier aspects of the camera may be off-putting for some, but I actually don't mind them, after all, I own a K-01
I have an irrational interest in that Tweed Grey KS-1.
For me, I'd consider a KS-1 because I actually do appreciate a lighter kit, hence the K-01. My main concern with the K-01 is that I miss the viewfinder maybe 15-20% of the time. Having a viewfinder again with improved autofocus and no-AA filter (I like very "crisp" images) appeals to me. Not $800+ CDN appeal, but appealing. WR would be a nice feature but in the years I owned my K20D for my own shooting style, WR was useful exactly once. And I only own one WR lens anyway, the DFA 100 Macro which is basically just my macro lens anyway.
I suspect I'll wait another year or two before I'd even consider picking one up.