For those who want a free program and one which works well try FreeFileSync. It can tell you which files are newer and you can select how to sync the files as well.
FreeFileSync | Get FreeFileSync at SourceForge.net . By the way this only works on Windows and Linux.
And yes, I'm waiting for a program which can actually work like Resco backup which backs up everything or at least everything except for the videos/audio.