From memory of the discussion at the AGM I think they were...

From memory of the discussion at the AGM I think they were talking about upwards of 95% yield at the time they said it was not good enough for acceptance criteria to be met.

Pixels can be excluded from the array at initial configuration if faulty. They can also be added to the exclude list later if they die during use.

However I think it is not just how many faulty pixels are allowable, but which pixels are faulty, and where they are. There is an issue about which pixels can be discarded at initial configuration because the pixel circuitry driving the addressing system uses rows and columns of pixels to save connections that would otherwise need to go to each pixel so they can be turned on/off individually. All very clever stuff (described in the patents). So I am assuming that if too many common pixels are faulty they cannot be turned off without compromising the sound quality.

However they also said that a chip with a given level of faulty pixels can still be sold and used for less demanding uses quite happily.