Just a warning for anyone doing an update; back up everything before updating!
So I did my backup (luckily), closed all programs, then installed X4 (easy). I started X4 and could not find my library; the update deleted my entire folder! the library (.enl), data folder, and output styles folder… EVERYTHING! 
I searched my computer for it, including the Trash, nothing. If the support team wants to look into it before it happens to anyone else, I was running OSX 10.6.6.
Cheers,