If anyone here has Comcast service with a DVR read this review.
I had a Comcast DVR for many years.  The first one lasted about 4 years then the failures started.  Replace box, works for a while then problems.  Fix problem, goes for a while then time to replace box again.  It was getting to the point the boxes weren't lasting a year before failing.  Recently I got the new X1 box.  Lots of new features but as usual the failures start again but this time it is not a failure with the box but it seems the problem is with the network outside the house.  The system has constant outages to some degree.  Sometimes it is a partial failure where some features don't work such as you can't fast forward your recordings.  Sometimes you cannot access your recorded shows.  Other times you cannot watch live TV   It is not the entire system that is out, just the X1 system.
So, if you are thinking about upgrading your box to the X1 box I would wait, as of now it is not worth it.  I have failures every other day, sometimes every day.
Thinking about going back to the old DVR system.

Mine sucks. It's started to get slow and sometimes get the please wait sign. These things are buggy as hell. Fuck comcast.

Directv is the way to go.