Would mRAW increase your burst depth?
If so, it might have its moments shooting sports action or BIF.
Do Nikon or Sony offer this odd little feature, or is it one of those exclusive Canon idiosyncrasies?
A few years ago I shot a public relations job and didn't notice that the camera (5D Classic) was set to small jpeg after an assistant had been messing around with it. That was a heart stopper. Oops! However I was amazed with careful processing how viable the files were for press release purposes, the client was happy. But never again.
Note: always check settings if someone else has been using your camera.
-pw