Couple of minor comments: - You obviously aren't the target audience, since you didn't even figure out that is also plots lean vs fat mass (very useful when you are working towards a target of getting fit without actually reducing weight or BMI). You don't stand on one leg in the delightful manner you hint at, just shift weight slightly to one side to move an indicator. The batteries it comes with are shocking, and last less than 2 weeks (normal decent batteries last for months), more evidence that you didn't really use it for long. Flicking the switch for kg/stone may be annoying, but you only need to do it once, and individual accounts can set up their own preferences.
Overall it is ideal as part of a concerted drive to change lean vs fat mass, or reduce weight as part of a new regime, and really, how often do you change your scales? Once a decade? A smidge over a quid per year isn't too bad.
(Paris - even she could figure them out.