-- William Gibson, All Tomorrow's Parties
That's really all I have to say.
If you're a printshop, you probably have a bunch of idiotic characters in your filenames. Some of these idiotic filenames have ":" or possibly even "\" in them, and the ":"? They're probably actually part of some stupid character's hex analog. And you can't just mangle the filename on copy because it'll cause linking problems with say, Quark.
So what do you do?
You stop using Samba and use NFS.
Just note that you'll need to use the -P option with mount_nfs on the OS X box.
I'll have a wrapper script for ditto by tomorrow probably so it'll do update syncs as opposed to simply copying every damn thing all the time (gah). Considering how slow this already is, I can only imagine that it's going to get a lot slower. :\