Raiding them will do nothing for you.
Raid 0 is a simple stripe across both drives. Speed will be limited to the slowest drive and as soon as one drive fails, the whole raid is toast (zero redundancy)
Raid 1 will give you a mirror which will again be limited to the slowest drive as well as the virtual disk being limited to the smallest capacity drive.
Though, if it manages to auto create the raid and will present the virtual disk directly to the system as (if I remember right) drive 0, this would be a good option with two identical drives as you will have redundancy should one drive fail. And provided the enclosure has external power as I’m not sure even a y-cable will give the required power to two drives given the onboard ports only provide ~500ma each.
I believe the Wii U only properly addresses the first drive in the designated port so presenting both disks will probably do nothing for you apart from presenting the first disk. Seems the addressing for iso lookup in cfw be it for Wii u or vwii is hard coded. Not sure there’s a way around this.
Suggest you use something like Wii U USB Helper and use the provided injections there or roll your own and run everything off the single volume.
Hope this helps you, mate
