I use my Tanita for a frame of reference, and an indication of hydration level. Others have posted about the ones with hand grip attachments etc. They may be more accurate WRT actual body fat, but I haven't researched it enough to have an opinion. I will probably get a new one with the hand grips etc., that ties into a fitness tracking app. I think that stuff like that is fun, and all helps with motivation, even if it's not highly accurate. I don't see the BC 50, but if it just uses the foot pads, it only measures impedance through your lower body, so probably pretty accurate (for your lower body) even though you lost belly fat.

Using the Tanita on athlete mode, I held 5-7 % BF for about 3 years but I doubt that I was actually that low. Of course many friends thought that I had a terminal disease during that time, so it was probably pretty close. I'm in the high teens now, and it may be closer to reality, but I weigh 15 lbs. more too.

If I get motivated to do some research, I'll try to remember to update this post.