More useful would be to know about the differences between Kantians, utilitarians, and virtue ethicists. Based on my utterly non-scientific, anecdotal method, my conclusion is that you're safest with utilitarians and virtue theorists, and in mortal danger around Kantians (it's that combination of dogmatic rectitude and lack of judgment, I guess--or to quote Geuss again, "The Kantian philosophy is no more than at best a half-secularized version of...a theocratic ethics with 'Reason' in the place of God" [Outside Ethics, p. 20]).
Now I myself have no strong opinion about this question. I know too few ethicists who fall neatly into these categories, and their character seems to me too diverse. My sample size is too small, given the variance! However, I have noticed that everyone I've spoken to so far who thinks there are differences in ethical character between Kantians, utilitarians, and virtue ethicists thinks the Kantians are the worst of the lot. I'd be interested to hear readers' thoughts about this.
I note -- though by itself it shows little -- that utilitarian and virtue ethics books are as likely to be missing from academic libraries as Kantian books, maybe even more likely to be missing: See here.
Although Leiter seems to speak tongue-in-cheek at the end of his post when he calls this a "weighty matter", I myself think there is no matter in ethics weightier than the question of what sorts of moral reflection are prone to encourage or suppress actual moral behavior.