You shouldn't be concerned about a cable box 'not upscaling'. Ideally, you should let it pass along the unadultured 'stock' content for each respective channel, then let the Samsung do the upscaling. Let Comcast handle the distribution of content and not the PQ, essentially.
If you truly have issues with how the HDTV or (X3 box) handles content, then look into a $3K DVDO scaler box
That said, price aside I really like the new X1 platform. The Samsung remotes integrate fairly well to with the Comcast boxes, so that's a good fit IMO and E thus far.
Understand, for much of the content passed along by the Cable/sat providers, simulated Dolby (etc.) can be adequate enough if you are worried about what comes out of your HT surround gear. You need to accept the limited nature of both audio and video feeds at this point in time. Additional bandwidth and upgrades by the networks/ISPs will solve some of this problem eventually.
I have both.. one was a work account and the other for my house... I switched work offices so now I dont need the directtv there anymore.
I have a samsung ku6300 4k tv. Nice 5.1 sound system with sony strdh770 receiver.
Which one should I keep? All I care about is HD, 4K and getting surround sound....
Xfinity X1 box seems to not upscale to 4k all the time and I get 2.0 stereo on a lot of channels.