Looks really good an seems intuitive (from just browsing the landing page). Will look more deeply.

Diagram-as-code option?

ie. a language syntax from which a diagram can be generated?

I find a lot of the time taken up in doing diagrams is laying them out properly and then having to rearrange them when it grows beyond a certain size.

This may,however, be an old-man Visio user problem that's been better solved by more recent options...