{{/path/to/img.png}} vs. Markdown's 
List syntax is nice and reminds me of wiki syntax. I've always favored that style over Markdown's list syntax. Actually a lot of it reminds of wiki syntax. Tables also looks like a breeze to remember how to write.
I like this.
You'd have to switch to Skriv's syntax for headers since Markdown's headers and Skriv's ordered lists use the same syntax. Another thing I'd change about Markdown would be to remove multiple syntaxes for writing the same element. For example, with Markdown you can use *, -, or + to create unordered lists. That might exist for some reason I don't know about but I don't like it.