I am a Fusion SE AWD owner and I have not seen any postings from AWD Fusion/Milan/MKZ owners concerning the PTU issue.
The following links are interesting:
Mexico: Ford sells Converca PTU operations to Linamar
http://www.synesismedia.com/WVMA/content.asp?contentid=62815
OIL LEAK FROM POWER TRANSFER UNIT TSB 06-9-6
http://www.fcsdchemicalsandlubricants.com/fad/tsb/0696.pdf