Yes, a mirrored (RAID1) HD is (or at least appears to be) a completely "natural" hard drive as regards format.
I installed mine in a USB enclosure, powered it up and attached the USB cable with some trepidation. But to my great pleasure I was able to see the entire directory structure and copy from it at will. Some .zip extractions, Word document opens, Help file opens later from the copied stuff I was convinced that all seems perfectly normal with the HD.

Something for the back of your mind.

cheers