I now own a HD DA 20-40 and have been testing it on the officially unsupported FF K-1. Here are some recent workings. I have to say I find it quite usable at a lot of varying focal lengths and apertures. Very pleased as I now gain a small zoom WR lens to add to my collection for those rainy days.
A 4:3 crop to assist with vignetting (i.e. at 40mm 3:2 even with a decent attempt at vignette removal is still problematic, but a crop to 4:3 isn't too shabby).
Pixel peepers, you are welcome; live.staticflickr.com/65535/32923668357_f24b973588_o_d.jpg