In Holland a dealer told that the 50 Hz tubes had the problem. So I would aim for a 100Hz, better tube, sharper image.
I bougth one myself and when you are used looking at the 100Hz, you see the flickering (is this good English?) at the 50Hz tubes.
I have a 100 Hz Avant and a 50Hz Mx 4000 and Mx 1500 and I see that the image on the Avant is much, much better.
You do not own B&O, it owns you!