I have the BD version of René Jacobs conducting Don Giovanni. It is a 5.1 24b/48k and the sound is stunning. Because of the video, the mixing is slightly different than the SACD version (not recorded with the exact same crew, actually) which makes singers more confined to the central channel in the BD disk.
Because of that, I prefer the SACD (for the sound only, obviously), BUT since the BD is 30% cheaper than the SACD set, it is actually quite promising for the future. That BD/SACD-set is a product of Harmonia Mundi, a most excellent recording studio.
I have a few other BD (Die Zauberflote, Cinderella and a few others I can't rememeber right now) at 16bits and, altough the sound is nice, it is nothing to fall off a chair; pretty much the same as a regular CD using PLII, a bit better, but not by much. Picture is good though!