Apologies if this is already possible, but it would be really helpful for me to save data nodes in a folder structure equivalent to the subject hierarchy (or maybe even arbitrary attributes) via GUI (Iām trying to use minimal code for a clinic-friendly handover document).
I know we can create a subject hierarchy from a folder structure, how about the reverse?
Excellent software, btw 
You can use this code snippet to save nodes to the file system in the same directory structure as the subject hierarchy tree.
You can run this script on a keyboard combination (see how to assign Ctrl+Shift+S keyboard shortcut here) or you can override the default save dialog (or just update the paths automatically before showing the save dialog), add a toolbar button, custom module (especially if you already provide a module for some application-specific features), etc. All these just require a couple of lines of Python script.
Thanks Andras for your very informative answer!