There has been a post over on the other forum regarding test shots from the new DA 17-70 on the Japanese DCWATCH website.
http://dc.watch.impress.co.jp/cda/lens_review/2008/07/18/8861.html
It seems to have gone largely ignored, but I have downloaded all 20 sample images and I must say they are very good. They are all highest res out of camera (K20D) images and as they haven't been post processed in any way are viable images for a true evaluation.
Here is a brief synopsis of what I think.
Lateral CA seemes less than the 16-45 by a reasonable amount. Looking at the images in SilkyPix and using the CA correction tool, the correction amounts at 17mm are typically 20-30% less than I usually need for the 16-45 at 16mm.
There is evidence of slight purple fringing in *very* high contrast transition zones, like leaves against a white sky, but still less than many other lenses, nothing to cause any concern.
There appears to be very little evidence of centering defects. In fact the edge to edge performance seems exceptionally good.
The distortion at 17mm seems very low, I would guess at less than 2%.
Sharpness seems very good at f4.5 and 17mm with little evidence of vignetting.
Colour is excellent, typical Pentax contrast and evenly saturated colours.
Bokeh seems a bit variable, in some shots it appears slightly ragged and in others quite smooth, appears worst at 17mm but still not what I would call objectionable.
In the mid range around 30mm the lens appears very sharp with excellent performance. At the long end it still seems reasonable, but I suspect it does soften somewhat at 70mm, but still not bad, even wide open.
If the production consistency is well controlled, this could be a very worthwhile lens to get. Certainly from the 20 shots available, I would have nothing to complain about.
Looking at the low apparent distortion at 17mm, it begs the question why they didn't squeeze it to 16mm, I would accept more distortion than it appears to exhibit at the wide end for that extra 1mm, it certainly seems much less than the DA*16-50 has at 16mm (and considerably less CA as well).
If the 17mm is generous and not an optimistic 18mm, then I would be very interested to replace my 16-45 with this lens. I hope to have one to try in the near future against my 16-45 and will post my results.