First and foremost, purchase your own modem. Not only will you be able to use your own router. They won't charge you $10 or $12 a month for their modem, a modem that will broadcast "xfinity" for other people to login and use.
Secondly, you have the option to purchase the set top boxes. And Comcast has to supply you with the needed devices to allow you to use them. However, I do not know the fees associated with that. It could save you a whole bunch, but it could be very close.
I have Dish and they are charging me $15 a month for DVR and $7 for each of their Joey receivers. HD for live is free if paid with a credit card. That is not an option with Comcast, so you'll have to pay for HD channels. Plus there's the fact that there are far more HD channels on Dish than Comcast.
I also have Comcast for internet and TV, package deal, but the TV boxes sit in the closet. I was even an installer for Comcast and did not like the new X1 boxes. Not only did I not like the interface. But I hated the lag they had. In training they tout the fact that each button press on the remote sends the signal from the box, down their network to their servers and back to the box to tell it what that button press is supposed to do. At first I didn't believe it, because it was completely stupid idea. But as I played around with it, because I wanted to learn it, I saw how much it lagged and if pressed too fast it would freeze.
Then there's always the 2 year contract with Dish. However, you can always change the packages during that time with out changing the time frame. However, if you change the equipment, say from Hopper 2 To Hopper 3 system, then that will extend the contract. But they are currently on the Hopper 3 and it came out in Feb, so they won't be changing that for a while.
The Hopper 3 itself has 16 or something like that, tuners. So that is completely feasible to watch 6 shows all at the same time using the Joeys. Plus being able to record 10 more as well.
