If you recall, I asked the seller about beta testers. He skirted the detail of the question and responded (finally) like this: "These batteries are the exact same model as the ones we've sold previously, the 5400mAh, and you can see by the feedback that near to none have had any defects or malfunctions. The only difference between the two is the larger power capacity to provide longer flight time."
Not a good or direct response (and of course the "feedback" has to do with the description, sale, communication and delivery - not the operation - of the battery).