Using some Hashsum generation tools we figured out that the depot between Mac and EU clients also seem to be absolutely identical:
forums.elderscrollsonline.com/discussion/125025/can-i-copy-game-files-from-mac-to-win8-pc
I also have to add that it is propably save to copy the .bik files too. They are the bigger ones of the non-dat files and it seems like the game downloads all language versiosn anyway. What is critical to identify the client seems to be purely minor text files.