How to compare a folder between Android phone and PC

Over the years I've learned that copying large folders from an Android phone (just dragging them, in MTP mode) to a PC isn't as reliable as you might want. So I'm looking for a way to compare the source (phone) and destination (PC) folders to check that a finished copy actually worked 100%.

This would be easy if Google hadn't taken away mass storage mode, and therefore the ability to mount the phone's storage as a drive letter - you could then just use any folder comparison tool, eg. windiff.

Has anyone got any suggestions on how to do this, eg. using Directory Opus? ie, how to compare a PC folder and a smartphone (connected by USB) folder for bitwise equality (I don't need a full diff-style report)?

I don't mind using a helper app on the phone if need be.

HA! I just discovered that Opus's synchronisation works on MTP device folders too, so that worked brilliantly.

And a Webdav server on the phone now gives me drive letter access as well (should I need it).