said by Debi Lee :well except for the Tivo S3 all other Tivo use one multi stream card. If the OP's TV can tune 4 digit channels would be the the only reason. said by ajwees41:
Cable cards are 2 way. it's the hardware that's one way. if your tv can handle 4 digit numbers you will be fine.
That's true. However there are multi stream cablecards (M) and single stream cablecards (S). Single stream cards allow a user to only be able to receive one channel at a time which means if a device has more then one tuner (TiVo 3) that multiple single stream cards are needed. Multi stream cards allow a user to receive multiple channels at one time so if a device has more then one tuner (TiVo Premier) only one multi stream card is needed. Now I think this means that if Comcast offers the first card for free, and charges for any additional cards, it would cost more to use multiple single stream cards rather then just that one multi stream cablecard which would be free.