730WD/Win 7 no problem. Seems as faultless as on Win Vista.
Win 8 is a problem for everybody, I haven't been able to test the 730WD on a Win 8 PC and it will need a very real advantage for me to use Win 8.

My Print set-up is for Europe but looking down the available list of paper sizes I see the dreaded 8 & 1/4 sizes (by 11" & 14") that for so many years annoyed the hell out of Europeans because printers defaulted to American sizes the minute you turned your back, with the inevitable edge/registration printing problems. hoto sizes A

I would think the print DLL would default to whatever you first set it to &/or it was clever enough to look at the OS country setting (default US!) But cannot test for that now.

Now I haven't played with double-sided that often but I did not see a "flip setting" for double-sided "reverse only" (or obverse). by default it prints upside down. I will look again, I will need it sometime soon.

What I found - even on the 730WD is that damp paper (as in "just printed") will not take kindly to the turn over wheeze. The print can (and does with posters) bubble-up just enough while still drying to make pages stick together occasionally. More so than my 20-year-old Epson Stylus 600. (Now defunct). The paper tray makes the difference IMHO.
For that method I tend to reverse side print one page at a time which is tedious, hence the attraction of double-sided. A partial result - I submit.

All in All I am very pleased with the PX730WD