Short and sweet; is there any point in mixing wired and wireless connectivity with a Mac Pro? Would this bump up/down speeds at all?
Nope, no advantage.
Why bother anyway? They both go to the same internet connection, which is slower than your wired anyway. If your wired was maxing out your internet connection, there isn't any bandwidth left over for the wireless anyway.
The thought was to use on NIC for uploading files (like Dropbox Syncing for example), while using the second NIC for downloading. I know in a server setup that is certainly possible and actually a great way to spread resources.
If not spreading upload/download resources, what other setups would you employ the 2 NICs for?