I am now using Ulysses to write my articles offline and then exporting to my Ghost blog when ready, which works very very well.
One thing that doesn’t seem export over well is the code block language. I have to go into each code block and manually change it to the required language, in my post, after export.
@omisnomis running a check on the HTML that Ulysses generates it looks like it doesn’t include any language information that Ghost can use to set the language. I’ll contact the developers to see if that can be added.