As an owner of one of the worlds finest commercial 6" APO's - an AP Starfire 152EDF which I have done some good observing time with under dark skies before relegating it to it's true calling (astroimaging) and having spent many hours at Wiruna at several SPSP's with high quality 12", 16", 20" and 24" dobs I can happily say the overall viewing experience through all the dobs left the views through the Starfire for dead - end of story
Of course as an astrograph the Starfire rocks and as mentioned gives text book perfect crisp stars and great contrast
Mike