UPDATE 2nd November 2012:
DLC Unlocker, extra outfits, weapons, etc!
has created his own patch aswell CLICK HERE
Multiman game settings:
-External or Internal
-BD-Mirror (without BD-Mirror is slower loading I believe)
-Discless or with Disc
NOTE:If you're having sound issues or returning to XMB, make sure you have a folder named "ASSASSIN_ISO" under "USRDIR". If you don't, simply make one.
Simply overwrite the 4 files with the ones in the fix.
I am using the DUPLEX ACIII BLES01667