That thing would give better results than the scales you stand on as it can get a better idea of upper body fat. However limitations such as hydration sensitivity still apply.
Body fat scales have a fairly large error, but that error tends to be quite stable for a given individual. Hence if you get a reading from a particular device, and have a contemporaneous measurement using another method which is more accurate then you can track changes in body fat using scales once you know the absolute error. As it happens, my Tanita scales said 18% at the same time as skin-fold testing said 18%, so I’m reasonably confident in the readings my scales give me are not massively wrong (currently about 15-16%, dropping to around 13% when I’m riding loads in the summer).
TBH, I’d have been surprised if you saw <10%. Elite athletes are usually in the 8-13% range.
