The question I have now is will this sound better than my Matt Roberts modified 701? It obviously has more tweakability but will that trumph Matt's magic?
My main issue with the 701 was the analog input section. The 701 sucked at that and Matt's normal mod doesn't address it. My problem has been that there was no head unit with optical out and full digital iPod control via USB (not the older analog implementations). I run a changer with my 701 via optical and the difference is night and day, but the iPod with all of my CDs ripped in 400kbps AAC is just too convenient to pass up on. Now with the new double DIN head unit coming out that has optical, a modded 701 might be a great choice, especially considering that it's not clear as to whether or not the 800 will do Dolby Digital/DTS.
Another thing to consider is that the new processor will require the controller. The new double DIN unit will probably control the 701 completely, just like my IXA-W407 does. For those who don't want to run the controller, the 800 is a bad choice since it has been noted that you cannot control all of the features without the controller, even with the new head unit.