Another option for having RAID without using software on the Pi could be something like a Drobo Mini. 4 drives, built in raid controller. They claim portable, although it is hefty compared to a two-drive option. But then again, you gain more redundancy.
so i'm failing to see how this is for travelers...why does this need to be a NAS? Why not just sync with an external hard drive?
I would think that 'for-travelers' would imply easy cloud storage and syncing