Too much is placed on the importance of "keeping MRV off the network". I submit that the whole concept is a red herring in a world of switched Ethernet.
Well, if you have actually tried using MRV over your home network compared to using over DECA, you might have experienced this issue. I ran MRV over my home network for more than a year before moving to DECA. During that time, if network usage was heavy due to other devices being used, I definitely saw some lag/stuttering during MRV playback. Once I moved to DECA, this issue disappeared.
If you're inclined to get all of your entertainment from DIRECTV, this may be a reasoned approach. Given that each TV has an average of one non-MRV device in the room with it, it makes the argument questionable as now you're looking to annex the cloud to carry content it wasn't designed to handle..
And yes, while rooms might have more than one non-MRV device in it, I would still submit that retrofitting a house/room for Ethernet is not always practical. The time and effort for me to run a CAT5 cable from my router to my bedroom means that it will most likely never happen. I currently use a Linksys WRT160N router up there as a wireless extender to which I can attach wired devices. It is not the best solution though. And while, it would not be a supported solution, I might consider using a DECA to provide a hardwired LAN connection up in the bedroom. In that case, if I am using the networked device in the bedroom, I will most likely not be using MRV so I should not experience any negative impact.
Today's problems don't worry me, I haven't solved yesterday's yet.
SlimLine-3 Dish w/ SWM16 (HD Service / WHDVR) / Full Setup
HR34-700 / Panasonic TC-P50G25 HDTV / HDMI / Networked - DECA / Family Room
HR44-700 / Samsung HCM5525W HDTV / Component / Networked - DECA / Bedroom
HR24-100 / Samsung HCM5525W HDTV / Component / Networked - DECA / Bedroom