Get a SD TV hook it up to your 811 via RCA cables and you will see that the 811's SD outputs are not any different than your 301, 311, 522, 510, 508 etc... I had to have a 27" CRT SD TV hooked up to my 811 for a week (TV was getting repaired) and the SD was just fine. (HD channels even looked fine on my SD TV) I guess the difference is in the TV, think about it the 811 is up-converting SD to HD and then your TV is showing all of the defects in the image. Better yet hook your VCR up to the SD connections record some SD content then play it on another TV and you will see that the image isn't any worse than it is on your 301.
Take a digital picture in low resolution and then blow it up to higher resolution and you will see the defects, I believe that this is very similar to what everyone is seeing with their HDTV's.