i see what you mean about the bpm. i used to have a gemini mixer with bpm's on it, and i got dependent on looking at the bpm read out instead of figuring out myself. when i've used djm 600 i usually have to switch it off.
but yeah the djm 400 imo is the best (2 channel) mixer out there. apart from maybe a rane or something or the Ecler Hak 380.