In my personal experience I have found impedance ones to be fairly accurate(~10%, BF range 10-16) and for most people the accuracy of full body ones is good to have a general idea about their body. Probably when you reach sub 10 levels, accuracy matters more.
Btw, here is the link to studies they give: https://inbodyusa.com/studies/
DXA is definitely less convenient, but there's no real reason to test your bf% daily (just like weighing yourself daily isn't productive, you need to look at average changes over time). Considering the amount of time it takes to significantly change your bf%, twice a year testing would be plenty.. and would probably cost you the same amount as this subscription service.
However, for relative changes over time when consistently measured, impedance works just fine (trending upward or downward).
I'm very skeptical of their claim that the photo measurements are more accurate than other means, but perhaps they've done massive validation of their methods and have achieved adequate reliability and validity.
Agreed, but for change over time it's just as accurate as skin calipers... which don't require an investment or subscription service.
In my view, impedance evens out with calipers because of the convenience of impedance measurements over time. I just stand on the scale for a few seconds every morning, and I have stats synced that give me a good enough idea of my status (bonus for the added understanding of my hydration which calipers won't do). There's no cost or subscription for my scale aside from initial purchase (Withings aka Nokia Body Cardio), and it is regularly available for as low as $99 on sale. So after a couple years and hundreds of measurements the cost is negligible given the benefit.
If I had someone regularly accessible to do caliper measurements, I would have it done to compare regularly but still continue with impedance because it's so convenient to do and track.
I only mentioned calipers because they'd at least show you trends, which is where impedance seems to fail. Impedance is simply a poor way to measure bf%. Hydration might be a different story though.
I'd recommend you do yourself a favor and just spend the $100 annually to see where you're at.
Regardless, I use it for all the variables tracked. I look at body fat percentage but body weight is ultimately the value of concern. I don't agree $99 a year is a good value just for bf%, because I do agree that visual impression means more than a specific number.
The subscription cost for Amazon's service may be a great value (privacy concerns aside) if their photo algorithm is within a couple points of DXA or hydrostatic.
If it's accurate enough, I definitely agree. I'm looking forward to testing it out once it's available; since I'm one of those data nerds with actual ongoing DXA results, I'll be able to compare the two accurately. Although, pessimistically, I think if they had proven results within a few points they'd be a lot more quantitative in their marketing rather than the ambiguous language in the posts referenced above.