The big shortcoming of SaBackup as far as I am concerned is lack of support for differential backups. By differential backup I mean over write files in backup if they are older than files in source and delete files in backup that are not matched by files in source.
Hey, your project is very good! I use SaBackup to backup all my data. The app works well, and does all the things that I need. I encorauge you to continue developing this app and if you need feedback, email me at firstname.lastname@example.org