Using DT markdown editor or external markdown editor, and inserting images in markdown

If with “linking around DEVONthink”, you mean “linking between documents inside DT”, item links are fine (I think). As long as you mostly want to use your MD files inside DT or on the same machine where DT and your databases are installed.

But keep in mind that they become useless if you use your MD files on another system where DT and/or your databases are not available.

Best to play around with it.