i have that one....i'd say it's best for measuring "progress" as long as you measure the same point everytime. As for accuracy, a one point measurement will never be accruate. Maybe if you can get a formula for a 3 point or seven point calculation, then you'll be better off.
I have a digital scale that says i'm 20% bf
I use the electronic hand held bf checker at the gym, says 14%
Calipers say 8-10%
I do not really think I'm lean enough for 8%