I'm normally on the mac side, so i'm still learning all the foibles of Windows and Robocopy. Anyway... Background: There is a Nasuni appliance (custom linux server running SAMBA 4.3 I think) at work ...

As far as I know, your admin friend is smoking crack. There is no difference in the SMB protocol between 64 and 32 bit Windows. Now between Windows 2003 and 2008 there might be a difference ...