However, I chalked up the unreliability to the "hot closet" and "laptop not designed to be a server" and "USB hub hanging haphazardly from a clotheshanger" aspects of this situation, rather than a manufacturing defect of the enclosures. So I decided recently to upgrade to a for real server and move all the disks over there, potentially putting at least some of them into actual hotswap SATA slots, rather than an ad-hoc enclosure.