Pitch: 529 Hz (!), meantone temperament, a bit of detuning = an organ/sample set with character. You love it or you hate it. Of course, you can avoid the D# in the fugue by chosing another temperament in Hauptwerk, I didn't. I think that Bach sometimes didn't avoid these chords with a meantone temperament.
Piotr Grabowski has added the detuning feature to several sample sets, which makes the recorded organs even more alive. For this recording I did set the detuning at 20%, not too much because I'd like to think that the organ tuner actually did his best.