I guess not all DVRs are created equally then, because when I was at my parents' house I was constantly frustrated by how difficult it is to fast forward through commercials on their Shaw-supplied DVR. The first level of fast-forward, which should double the speed the video playback, almost appears to slow it down, then jumping to the second level makes it skip fast enough that you're likely to have next week's Lost spoiled for you. A few years ago there was a button to skip exactly 15 seconds, which made it very easy to skip commercials, but they essentially disabled that button quite a while ago, and since then the fast-forward / rewind capabilities have gotten gradually worse. I'm not sure how many people use DVRs supplied by their cable company, but the ability for the company to push updates to essentially cripple your machine is something that needs to stop.
Me, I'll stick to downloading everything with the commercials already stripped out.