I agree. A hard reset is best before installing his pack, and worst case, you will need to delete the mail account and reinstall it. Just save the file to a memory card, do a hard reset, install his cab right off the bat, and then setup.
Can't wait for the HardSPL to be broken and we can get our own ROMs. It was nice of him to pack most of the reg tweaks and current adjustments in to one file, saved me from having to do it