Vis-à-vis the USB vs. Thunderbolt question, OWC replied:
So far, it seems to be limited to the Thunderbolt connection types. USB 3 should be fine.
It isn't just Thunderbolt, apparently, because I have on OWC Mercury Elite Pro Dual connected via Thunderbolt and have had neither disconnects nor kernel panics with it. This device is RAID capable (although I don't use it that way) and is older than the dock. In fact, I bought it at the same time that I bought my iMac, in early 2015.
