I have had the pleasure of listening to both and there are some differences worth noting. The B50s seem to be a little more tricky to drive - weak amps = poor results. They need some room from the back wall to open up, so room size is important. The 961s work well with smaller amps - too much power and you can break them up. They also are less sensitive to room placement.
Overall, I think Rocco is right. Burmester at any level sounds very good, but stepping up their product lines always reaps rewards. If you have the room and the amps, I would go after the B50s.
Overall, I think Rocco is right. Burmester at any level sounds very good, but stepping up their product lines always reaps rewards. If you have the room and the amps, I would go after the B50s.