It transpires that a lot of the political blogs out there edit the comments so that some of the political spectrum isn't represented. For example, Taxpayers Alliance tend to edit out the left-of-centre comment, while Richard Murphy's Tax Research UK blog edits out the libertarian far right. There are arguments for and against doing this, I guess. On one hand it can focus debates more and stops an endless repitition of (say) libertarian vs social-democratic arguments which are usually pretty fruitless because the two sides start from such different perspectives. On the other hand, clearly it's, within the context of the blog, an impediment to free speech. Obviously it's not a global impediment to free speech because people are free to comment elsewhere, or set up their own blog. But nonetheless it does close off debate somewhat, and something like the Guardian's Comment is Free is more eclectic as you do get a wider range of perspectives (although one always has to put up with a particularly high percentage of omnipresent right-wing trolls, and this tends to turn a lot of left-wingers I know off CiF, so paradoxically, free speech can discourage comments as well).
For my part, giroscope only edits out obvious spam comments and other stuff which is so defamatory as to be outrageously offensive (I don't think I've ever had a single comment of the latter type in 4 and a half years, though). Partly because I find that a lot of the nutters who crop up add variety, and stop it being just me talking to myself. So do feel free to comment away.