Totally subjective. I prefer no extra DSP and most of the time let my AVR select based on the signal received. Not many 7.1 mixes out but boy I love em when they do come around! Really make a big difference, the ones I have played. I do occasionally try the PLIIx and for awhile tried out the PLIIz with some front heights. For my setup the Heights did not do much. The PLIIx is okay but not the same as a real 7.1 mix. Really try them all for yourself isn't that why you have all those bells and whistles?