It's probably somehow technically inferior on paper but when using the pitch shifter as a downtuner for Brutalz (which is about 50% of what I would use one for... the other primary application being that EVH detune thing); I prefer the QC's shifter to FAS, Helix, etc.
I am not making any claims re accuracy but whatever it is that is 'off' about the QC's shifter as a downtuner, I find it to be more agreeable qualitatively than the competition. I have d*cked around with the FAS one the most... Like trying to control it w/ envelope, etc.
That said, I generally would not use a pitch shifter to drop more than two steps and generally avoid it anyway unless retuning is not an option. After that it is just the EVH thing which most of them do well enough for me.