Yes, I downloaded JKSM half an hour ago and made my mind about that. In this thread, I only read about keeping saves safe and importing saves from "outside", but no one (I think) ask for multiuser pupose. In fact, I suppose I am looking for a more "kids friendly" tool : I can manage my backups and restores by myself with JK's SaveManager, of course, but I won't ask this to my kids.
I've got a clear idea of a program that would allow what I seek but I don't code myself... need to learn on 3ds, I suppose !
Here are some features I think could improve JK's Save Manager:
Allow to "full save" instead of single "Save" or "ExtData" export
Allow for time "YYYYMMDDHHMM" text chain shortcut (allow for strict alphabeticaly sort = time sort, very common in logfile names, time index, ...)
Allow to specify a template chain to automatically generate saves filenames based on date & time, game title, game id,...