I'm intending to update both my internal drives with the WD RE3 500gb versions as I've just had a WD 160gb fail which is outside the warranty. I was thinking of using another RE3 in a caddy as an external for backup of important data along with Acronis for hopefully failsafe reasons. Would a different drive be better to use in the caddy than the RE3 as it wouldn't be used in RAID operation?