Bodpod isn't that much more accurate...
Did you set your Tanita to the "athletic profile" as you did your settings? ...readings for athletes get better then (but I would imagine that people with alot of muscles might get an more inaccurate reading, especially if one would use AAS...
I have a Tanita bf-scale as well, I have serious doubts about it. But I didn't buy it to get those super-accurate reading, but to see "about-ish" where I am. But they are funny... In the morning, before eating anything, I have a higher bf%. Then during the day, say after lunch, straight after eating and drinking. My weight is up and bf% will be up to 4% less... I chalk it down to amount of salt and water in the body. But one would think that you would actually get a more accurate reading in the morning... Since that is when your weight reading will be the most accurate...