My experience has been that while Catholics and Jews can argue on and on about transustanciation, kosher, the meaning of baptism and a hundred or more theological positions, most Protestants don't really think about more than one issue per sect at most. Baptists think baptism but immersion is really important, Seventh-Day Adventists are insistant on the Sabbath being Saturday, but other issues are just not worth fighting over for anyone but the preachers. Jehovah';s Witlesses are the exception: they have dozens of disputes with tradition.
Mormons mostly only want you to know that they are not polygamous anymore: the days of Bigamy young have ended. The weirder bits of Mormon theology seem to be rarely discussed.
Mitt Romney might or might not be a great president, but I don't think his being a LDS would have much to do with how he'd run the country if he were elected. It might, however, provide a huge warchest that would help him get elected, or an "expose" of the LDS Church (Jon Voight is making a film of the Mountain Meadows Massacre, due out very soon) might cause many to vote against him.