Oh ok. There seems to be a 3.11.1 version for the P780 on miui.com though :
http://www.miui.com/extra.php?mod=download/rom&fid=350
Downloading it right now. Pretty sure it's different from the 3.10.18 I currently have on my phone as file size is different too.
By the way, pardon my ignorance, but is there any difference between the unofficial miui roms from miui.com and those on xiaomi.eu ? (talking about the regular roms, not the multilang ones). I have been led to believe that the English roms on xiaomi.eu are only English and not Chinese/English as those on miui.com, but may be I did not understand it right and some got lost in translation too