I did exactly this back when 23andMe switched to a newer chip. I signed up for a second account and matched with myself as a full brother. The old chip account

I did exactly this back when 23andMe switched to a newer chip. I signed up for a second account and matched with myself as a full brother. The old chip account had less data points (health items, etc) but most of the data was about the same. My wife did the same with the same result, as did a friend who had purchased the original 23andMe kit and wanted to get the newer data from the new chip. So while I don't doubt the accuracy of the linked article, my anecdotal experience is that the 23andMe DNA tests have repeatability at least.