If they have sold out (or near) the smc ltd's my guess is that they have to use HD. Keeping the old smc running is probably costly. HD is supposedly a cheaper and better coating. If they can lower the prices of the LTD's beause of the long running production and now cheaper and better coatings perhaps the limiteds can find a new, less high, end spot in the lineup.
I've repeated it many times that the ltds is a strange lineup that cause a fair bit of trouble for Pentax. Of course they are also a agreat asset but they are simple, old designs with performance issues whilst priced like high end glass. The ltd's leave Pentax without a low/mid priced prime lens lineup which I think is a problem. So pushing the ltd's down to a fantastic mid priced lens line would be great news for Pentax. With a middling price the purple fringing and screw drive focus would be completely forgiven.
Originally posted by Pål Jensen Mine doesn't have fringing
You are then either poor sighted, very uncritical or shoot such a limited set of subjects that you never stress the lens. It still seems like a beautiful lens though!
Map camera did some test showing how HD supposedly improved the fringing on the FA 35mm f2. Scroll down to the shot of water and a jetty/pier in the middle of this page.
https://news.mapcamera.com/maptimes/%E3%80%90pentax%E3%80%91fa35mmf2%E3%81%A...0%B2%E5%8C%96/
^that shows a significant improvement but I doubt it's consistently that much better. We haven't hear much about less ca with the HD DA ltd's?