Right, but the question remains, which is closer to ideal, the fixed 2048 offset or the measured black levels? Seems to me like using the masked pixels makes it quite prone to noise mostly at high ISOs, and that they deviate from the fixed offset in statistically insignificant ways (while the ideal offset might well remain the same), which is why I'm thinking the measured black levels should probably be disregarded entirely, except maybe as a hint of what the true fixed offset should be.

But since you're using the measured black levels instead then you must think that logic is wrong, this is what I'm asking about.