If all you really want/need it for is running this specific save file backup/restore tool I don't know if I would recommend dstwo. I'd always recommend cheaper options because while money might not be an issue, sometimes it can be a bit overkill haha. DSTwo is the reliable option for general use, with Acekard 2i being much cheaper and more-or-less just as good (not 100% sure about it running on higher 3DS firmwares though, but should work on regular DS/Lite.) You can still go with one of those R4 clones since they're even cheaper, but you'd have to look around and figure out which ones are good and which ones are bad. As long as the flashcard is functional and can do the bare minimum of loading games w/ DLDI you'll be fine (but then again, I can't really help when it comes to R4, I don't personally feel like they're worth the headache of figuring out.) But yeah, you need the flashcard to run the homebrew, no way around it.