One DUer in particular was so shocked when I said something positive about Margaret Thatcher, for example, that they were still following me around and bringing it up months later.
Also, my support of free trade and the Citizens United decision is unpopular among quite a few DUers (notwithstanding the fact that Barack Obama is a big free trade enthusiast and the ACLU supports Citizens United).
Like you, I try to stay within the community standards and am generally successful. And I agree that if the site owners decide they want less controversy and debate and more people agreeing with each other, that is entirely their prerogative.
I kind of have a reverse Groucho Marx thing going on here. If DU ever bans me, it means that it has become so boringly uncontroversial that I wouldn't want to be a member anyway.