Well, I won't try to talk you into or out of anything. It sounds like you'll be perfectly able to compare D* and Comcast for yourself, side by side, and make a decision based on what's best for you. I myself was pleasantly surprised at how good the picture is on Comcast, not only the HD, but the SD channels 2-99, as well. Of course, after 4 years of HD viewing, we don't watch too much SD stuff anymore, save for the nightly news, and some Food channel and HGTV stuff which my wife likes. Hopefully we'll have them in HD sooner rather than later.
And as far as the dvr goes, again, that'll be for you to decide for yourself. The new non-tivo dvrs which D* has gone to have had decidedly mixed reviews. I absolutely hate them, and that's one of the prime reasons I have switched over to cable. Others have had a better reaction. The Comcast Motorola box which I've been using is also no tivo, but as a secondary box it's worked pretty well for me, and I've even begun to appreciate some of the OnDemand stuff they offer. I use a tivo series3 as our main dvr now, and it's top of the line, but pricey.