My experience may help.
Started with @Home near the turn of the Century, which was taken over by ATTBI [not sure of exact name anymore] then Comcast acquired. Have had Comcast in 4 locations in the PNW and that includes two States. Did have DSL for a year from a small Co-op way out in the country [best service I ever had, though only 1.5 meg]
Where I am now, I have had the most outages so far. Some lasting up to 5 hours. I was able to call the Comcast number from the phone registered to the account and the "system" advised me that there was a known outage every time, with an ETA. The last time, it also included TV. I have just watched DVD movies till it returned.
Did have a problem with speeds late this summer and suspected that the line "I had run" was the culprit. And it was. I originally ran the line myself, just for TV and for that it worked fine. I used some "crap" connections and leftover cable for a 75' run. Over 3 years it degraded. My speeds were erratic at different times of the day, per various speed tests. Called support, let them do their thing, and they sent a Company Tech the next day. Since the line was in the attic and furniture was in the way in the room where the Modem was, made access easy for the Tech by moving everything out of the way. And having the Laptop connected to the Modem directly when he came.
We ended up by putting in a new splitter and ran new line from that to the modem. Before I had 3 or so barrel connectors and some crap connectors. I helped the Tech. as much as I could. I could tell that he appreciated that as it was toasty in the attic. Plus it put us on an even playing field, so I could ask questions and get good answers.
Ended up with speeds higher than my Tier, wirelessly and more so once connected directly to the modem.
Was never told what the cost was to be at the time of the call, but it was only $32.00 or so on the next bill. Best $32.00 ever spent. And he was here 2 hours. He fixed a couple of other issues that would have been problems over the next couple of years for cable going to another room where the main TV is.
So what is the takeaway from the story? - help the Techs and they will help you, whether on the phone or in person. And one can learn of new tools they now have. Just that week the Tech had been issued some slick ones to do his job.
Plus it probably does not hurt that I have provided Tech Support for USWest/Qwest, GM, Sprint/Nextel, Vesta, and a bunch of other companies. I know what the person can and can not do on the other end of the phone line. And assholes did not get very far with me, I would help them, but would not go out of my way. It would hurt my call metrics. Nice people? I bent over backwards and could have several hour long calls per day, without hurting my metrics.
I do realize that different areas of the country have different levels of experience with Comcast, but so far, in my area, I talk with local people in Tech Support.
I can get CenturyLink where I am at, but reading the reviews and talking with others in my area as to their problems, will stay with Comcast for now.
Good luck solving your issues!