Mirrored RAID is sort of worthless for most all users as anything bad happens gets immediately copied to the other drive.
Your better off with scheduled clones, this way every so often it will remind you to hook it up and update it, or leave one hooked up and it will update itself.
You get both hardware AND software protection as you only update when you know it's good.
Also you can keep several clones backdated, and they are all independently bootable.
Thanks ds store. I was hoping to remove some clutter from my desk by getting rid of all the external drives and using only internal ones in a RAID configuration. But your point makes a lot of sense, so I will stick with what I have now.