What would be really cool is if you can cut-n-paste an existing diagram (possibly also with comment markers) and edit it. Then cutting-and-pasting it back into the source code.

When you draw 2 boxes and an arrow between them, then move a box, it does not stay connected to the arrow. I think that is an instant no-go for designing diagrams. Perhaps it can be used for converting to plain text diagram, but not for working on diagrams and changing stuff around a lot.

ThankYou for mentioning this! I always wanted something like! It will save me soo much time and effort!