What kind of speeds do you get, and how much storage approx?
I’ve gone the route of raiding usb drives before, but 5/10/40gb ports didn’t exist so it was always slow and not worth it.
Sounds like you basically have a DAS that connects over usb, that’s pretty cool if it works well.
Oh also, drives have become a lot better at handling heat or at least are more reliable imo. If you can, try to stick to drives rated to go in a nas. I used to have drives failing all the time, but not so much over the last few years.