How can you sync "learned spellings" between Macs
The spellings are located in various files in ~/Library/Spelling. Namely, LocalDictionary and various localisation files such as en_GB. You can sync this entire folder using a sync method of your choice.


To sync via iCloud, symlink the folder to/from a folder in ~/Library/Mobile Documents.
To sync via Dropbox, symlink the folder to/from a folder in your Dropbox.