Although Pentax did not admit that it is a FF lens, a new DA50 owner and Pentax user has tested it on film with a MZ-3:-
http://forum.xitek.com/thread-1043959-1-1-1.html
(in Chinese)
See the posted samples, I think no one will disagree that it is not a Full Frame lens. The IQ, sharpness, colour rendition and bokeh etc. can also be inspected.
Now, we have one more FF compatible lens in the current Pentax lens lineup, the full list is updated.