I just moved from the Cupertino Comcast in the San Jose CA area to the San Diego CA Time-Warner cable system. The installation of the new cable cards on my S3 was a snap. Worked first time. And I didn't have to argue with the installer about the fact that an Internet connection would be lots faster than a dial-up connection like I did in Cupertino.
An interesting side note is that Time-Warner wanted the MAC address off the cards as well as the Host ID. I remembered that the debug screen showed the MAC address - so I didn't have to uninstall the cards to get the address off the label.
One downside is the web based online scheduling. Apparently, once cannot change the web based schedule via the web. Customer Support told me that it takes up to 48 hours and several TiVo to server connections before the web interface reflects the changed cable lineup. Note that the lineup on my Series 3 is correct. The lineup on the web is wrong.