joeh - I assume what you're calling "blotchy" is increased pixillation, which I generally attribute to momentary signal degradation/loss, tho' it certainly could be an artifact of compression. I haven't noticed anything more than usual, i.e., the blotchiness on SD channels seems about the same as usual for me: some more, some less. My "HD" hasn't gotten any worse either.
If I sensed a change, the first thing I would do is look at my signal strength to see if that has degraded any. You might need to watch it for a few minutes on each satellite to see if it's fading in and out. I "baselined" my performance when the 811 was first installed in case I need to compare it later but so far I haven't had any issues worth checking. That may change for me when the leaves are back on the trees, affecting my 61.5 dish...