If you want the quickest network performance between OSX and the Raspberry Pi (very quick on Openelec)
I strongly suggest you download:
NFS-Manager
NFS in already built into OSX already, NFS-Manager is just a configuration editor.
Once this is up and running follow this mini guide and select only these options below: (Ignore the DNS window that pops up, has never seemed to affect me)
NFS Server
Share Definitions:
Hit + and then the "Select" button and choose your folders to share.
Then below the Shared folder window
Options: deselect (untick) Share "read only"
Tick - Allow clients to also mount objects in the shared folder
User Mapping: Don't map users
Minimum Security: System standard only
Access Permission: Allow access from any network computer
Hit "Apply" bottom left and you've configured your shares, you can now close NFS Manager
Now in XBMC go to the Video-->> Files Menu -->>Add Videos -->> Browse -->> Zeroconf Browser -->> Your Computer Name (NFS) -->> Select Shared Folder -->> OK
The subsequent windows and settings are up to you.
Thats it, easy once you know how!!