Tivo Bolt w/Comcast Xfinity SF Bay Area Video Quality vs. DirecTV

Hi,

I am close to switching from DirecTV to Comcast Triple play w/Bolt as I pay almost $288 per month for AT&T phone/Comcast Internet/DirecTV.

Would appreciate any feedback on those that have also made the switch and if you see a noticeable difference in picture quality (DTV vs Comcast SF Bay Area - I'm in San Jose).

Also, I heard Comcast is switching to MPeg 4 and would like to know if picture quality is any different after the switch.

Thanks,
David