Agree Richard, but I have found that SOMETIMES DSS won't fully "denoise" an image, despite how many sets of DFB I apply, and I have overcome that by using in-camera noise reduction ON and THEN applying the DFB. Works for me anyway
I did find doing GX work that PRE-processing DID improve the stack result, quite nticeably. From NO dust lane visible with a no-preprocessing DSS stack to VISIBLE dust lanes, and better star colour in the arms (from NIL blue showing to blue showing)
Whatever works I guess. Your results may vary