I've been using a HDHomeRun Prime since around last Christmas when I got it from a Black Friday special. I have it located in the basement near my server and network panel right where the cable comes in from the street. I have it serving 3 HTPCs, one extender and a few other desktops/laptops running W7MC.
So far it's been brilliant. I too have Comcast. I picked it up at my local office and did the self-install. Everything actually worked and has been working ever since -- way better than the set top boxes ever did.