as you said they are good to mark progress every few weeks and to make sure you are not loosing muscle mass, but I disagree with the electronic scales...they suck, I have used different home and professional modles that have cost over $6,000.00 and have read my bodyfat at 12% at one week out from my bb show, in which I had striations in my back and ass! Any number of componates can effect the electrical test, like too much muscle compaired to the normal male, large intake of water can effect results, dehydration, or the use of chemicals such as Sterids that can make you retain extra water...