It does not seem to be much of a downgrade if it is only 10 hp and 10 ft-lb. I am more concern about the 8 speed transmission since way too many on this site complained about the lag.
Nevertheless, has new engine specification been confirmed. I thought it was just rumors. Lets not read too much into it until BMW release the data.
2012 BMW X5 Vermilion Red Xdrive35d with Premium Package, 3rd Row Seats, and Adaptive Drive