Actually, I decided to re-rescue the box, make the patch and deploy it (with non-precious data). I dug up four 3T SATA drives (most of mine are larger and SAS). This will give me some idea as to how long the device continues to behave (if "a long time", I may consider rescuing other similar items in the future).
I will gift the box to one of my colleagues at our next offsite (with an appropriate back-story lest he rely overly on a box that might s*it the bed at any minute) so I can get some longer-term feedback "for the cost of a PUP".