The picture quality all depends on how the source provider sends the channels on C-Band to the distributor. The old saying Garbage in, Garbage Out applies here, just as it did with AMC packing four MPEG-2 HD channels per QAM slot last year.
The .TV channels originate on AMC 18 at 105.0 degrees West on Transponder 11. The six HD .TV channels share the transponder with three other HD channels and two other SD channels. This makes for a C-Band transponder with 9 HD channels and 2 SD channels encoded in MPEG-4 with 8PSK modulation and 5/6 forward error correction yielding usable bandwidth of 75 MB/second for the entire transponder, compared to only about 39 MB/sec for a QAM-256 RF channel. IF the entire C-Band transponder were to be carried, two QAM-256 RF channels should be allocated for no loss in picture quality. The average bit rate for the .TV channels should be in the 6 to 8 MB/sec range. Therefore, the best configuration would be to load five MPEG-4 channels per QAM-256 slot, which is exactly the ratio being used for MLB, NHL, NBA, and Spanish MPEG-4 HD channels. Even though the .TV channels have been transitioned to MPEG-4 for FiOS delivery, they remain loaded only 3 per QAM slot (this will soon change) so there is plenty of leftover bandwidth right now. This would imply that the quality of the C-Band source is substandard.