I'd suggest doing the symlinking manually to see if you like the results before doing all of the work to automate it. For Auctioneer I personally don't want it running on slave accounts, so sharing data between WoW instances wouldn't help me. There are some addons where I wind up having to make the same changes 5x times, but I usually find that faster than dealing with the annoying conflicts from a last write wins situation. YMMV. GL!