Brilliant work, I would just nitpick one detail, which at least for me degrades a little bit the stunning picutre- the black point is black BLACK at your processings, by my taste I would appreciate to see a bit rised black point. With white point set slightly bellow and black slightly above the full range, you will get kind of more pleasing smoother appearance, and I am sure it will be one of the best M31 we all have seen:-)