The last time I tried to get a cablecard installed was a disaster — A Little Ludwig Goes A Long Way: Comcast Cablecard Install. Things have gotten a lot better. I recently installed two cablecards from Comcast in two different Tivo3s and while it was crazy arcane, it could all be done over the phone and it worked. You have to record all kinds of goofy numbers and tell them to a Comcast rep over the phone, and then wait while they do some mysterious network authentication task, but then things work. Finally got rid of that disaster Microsoft TV box.
Apparently I am not the only person rediscovering the cablecard. And as noted, the cool thing about current cablecards is the multistream capability so that I can record two channels at once. You can’t get Comcast PPV/Ondemand content, but you can get Amazon Unbox.