David was referring to 'Hardware dependent' setups, where the RAID card or motherboard based RAID will only be recognized by the same line of hardware - not able to cross between manufacturers. Software RAID runs in the OS, so it requires hardware, but it doesn't care who made the SATA port it's plugged into. The screwey stuff is the software RAID implemented in hardware - think most BIOS setups, or the old Promise 0/1/10 controllers. It's software, but it's implemented in the hardware, not in the OS.
RAID1 or mirrors have specific uses - as in I need to keep working in the event a drive takes a poop on me. Like all storage setups, RAID is not backup, so file corruption can still happen, and it's going to effect both drives the same. Cloning/syncing is a great backup method, but make sure it allows for versioning, otherwise you'll need a whole separate backup process.