If you root an s3, you won't lose your files. It seems you don't on any Samsung devices. HTC decides cause the phone to wipe once you unlock the bootloader. Hope this helps
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I don't think it is compatible with the Jellybean Roms but I don't know it. You can try it if you want but make a Nandroid backup or at least backup the NFc.apk and Nfc.odex before you try.
I am going to create the mod also for the Jellybean ro...