You can already do this by using the USBMass plugin and using the drive letter option to change it to your drive.

I could swear this had been posted before, but searches didn't turn up anything. I was really hoping this would make it to 4.0, but I don't see it there either.

I, like many, have 2 music libraries, lossless (FLAC) and lossy (AAC). I would like an easy way to synchronize the 2. I rip everything to FLAC, then convert to AAC. I keep the FLAC files on 2 mirrored external HDs that are not typically turned on.