To me, the most terrifying thing Obama ever said was that the founding fathers / Constitution lacked the insight to empower the President / Federal Government to bring peace and equality to the American people. He doesn't just lack an understanding of the principles of limited government, but seems to measure the greatness of a country by the size of its bureaucracy. This also seems to be his practice. Not that I would set him too far aside from some past presidents, but he really brings attention to it like never before.
You say that he would never be a Lenin, Stalin, Hitler, Mussolini, or Mao, but for what we can look back upon as having been so terrible, they were not so greatly criticized while in power. Most of them achieved the level of power they did because they were beloved by their people, devoted to their ideology. To my understanding, the principle of conservative values is government should only be powerful enough to enable people to take responsibility for their own lives and collectively for each individual to protect their own private property. People can be rational when it comes to decisions that will affect their own lives because they alone bare the responsibility. When others are granted the power to make decisions for other people and their lives, it is only well intended without consequences for the decision maker. None of those "monsters" of history would be who they were if not for the idealists that empowered and enabled them. So I don't think it is a question of whether or not Obama is any of those people so much as whether or not he is being enabled and empowered by an ideology only all too similar of a history we were asked to "never forget".
(note: I will post a link to the video when I find it)