I had my logic board replaced and can no longer read the searial number, get "SystemSeumb" where the serial no. should be. According to apple, all the replacement logic boards have blanks where the serial no. is and they have no way of coding in the old serial no. onto the new logic boards. They suggest reading it from "under the battery area." Ya. ok.
Thus a brand new computer, with a brand new replacement logic board means that the computer is LESS effective than before. As a colleague said, no longer being able to read the serial no. in the system profile is just "tacky"
The change of board also means that SMC firmware update must be reinstalled as must firmware update 1.0.1 - which you may have installed previously. They certainly didn't do this in the shop - or leave a note to say be sure to install these two firmware updates - one of which does NOT show up in software update.
The new board also changes your ethernet MAC address - so if any of your systems require your mac address to identify you on the network, check that, too. At least that no. shows up in the Network system prefs panel.
Tacky is right.