Personally I have never had to delete and re inject save data in order to get mods to work. Smash Selector doesn't really do much with actual patching, its basically entirely saltysd and luma3ds's code injection at play. If it was a problem with Smash Selector, it would be a pretty white or black problem where it either loads or it doesn't. There is one problem that it might have, and that is the fact that the download of the saltysd might be corrupt. So, i'm working on a slightly new version that generates the sha-1 hash, so it can be compared to a non corrupt version without having to upload it and compare files manually. Im almost done with that new feature, but im still debating on whether I have it download the correct hash to the 3ds to display or just post it on the main page of this thread.