I'm thinking of getting a Courier as a diaper bag.... does that sound or look silly? I like to wear my cross-sling bags low, does anyone know how long the extendable strap is at its longest? Lastly, how do I tell whether a Courier (on eBay) is authentic? There doesn't seem to be any notched rivets on Couriers, which is the lazy and easiest method for me in differentiating auth from fakes. Does anyone know what to look out for and what the serial/model no. should be? AtelierNaff doesn't have much info on Couriers. Many many thanks in advance!!!