I don't read the comments on SSC mostly because of very, very poor comment section layout (because nesting comments just significantly narrows the width for every "child" comment), not because of comment quality. Besides, if I perceived SSC comments as rather poor in quality, it would be mostly because of the significantly larger contrast between them and the main blog post. (At least here in Discussion, it's rare when one LessWronger in the main post writes significantly better than the several top commenters, whereas on SSC, Scott is, well, Scott and everybody else is just everybody else.)

Besides, I don't find the addition of a up/down vote feature an improvement, rather the opposite, especially when it comes to the kinds of topics Scott touches upon. I often don't use my own up/down vote buttons because I often feel like "who the hell am I to judge?", particularly when I know I lack expertise in something. Other people, also without qualifications, may not be as scrupulous. While it does clutter up the comment section, agreement or disagreement expressed verbally, non-anonymously (because it psychologically weighs differently depending on the impressiveness of the person it comes from), and with justifications seems to me to help the overall quality of discussion.