I actually wrote a tool that automagically xcopy's my addons across after I run an update on one box. Basically it's a glorified xcopy that just doesn't copy mods to the alt machines unless the mod exists already.

As for your comment about mods acting wierd between the two accounts on the same machine, that goes back to some mods storing their variables on a system-wide basis. The mods that store the data on a per-character basis are easy as you just copy your WTF stuff over and you're golden.