I found a neat little homebrew app the other day.
Its DS2Files its a little app which lets you delete files from your memory card from the DS.
This is pretty useful as with the N-Card I need to plug the Card and the DS onto the PC and delete the file. I can now delete the file on the fly, so if i play a dud “backup” and don’t like it i can delete it on the spot without having to plug the memory card onto my PC.
Check it out, it should work with the R4, M3 etc.