On the textualcriticism discussionlist, Arie Dirkzwager draws the attention to Young Kyu Kim's article "Palaeographical Dating of p46 to the Later First Century" which is available online here.
Arie asked for comments on the article. For some reason my reply to the discussionlist is bouncing back so I have to reply offlist to Arie. Anyway, Kim's article (and the dating of P46) was discussed on the old TC-list, and the particular thread was started by no other than the founder of the new textualcriticism discussionlist, Wieland Willker:
... followed by several other messages in the thread.