Your old DME is MDS80. The new one is MDS81. The newer DME has special anti tuner SW loaded onto it. Its harder to crack/tune - but most places know how to get around BMW's lockout.
I would keep your old DME... if you ever wanted to put a flash tune on it... it would be very easy. Most of the coding guys can do it. There is a boot-legged Alpina flash tune for these early DME's.