I've been tracking these complaints carefully, and will continue to do so, but from what I've seen, I think most people are overestimating what UV should actually be in December (depending on where you live, but still...). I'm actually shocked by the variance I've seen from some other units I've tested, and how high they run. If I took their word for it, I would need to be wearing a whole lot more sunscreen right now... in Wisconsin. In December.
Full disclosure, throughout all our testing and revisions and then final units in the field, I have seen a very, very small number of exceptions where the UV sensor seems suspect. But for the vast majority, I think we're just suffering from a crummy case of Early Onset Winter-itis.