The main difference between a caucus like Iowa and a primary like New Hampshire is that caucuses are open and primaries consist of votes in private (my thanks to NPR for that insight).
While people may advocate for Obama in an open caucus, there is no disincentive to voting against him in a private vote like New Hampshire's. This is something the pundits all missed in their predictions of a double-digit Obama win after his 'surprise' win in Iowa. At the same time, Hillary, for all the strengths and experience to which she lays claim, is simply too divisive and polarizing to engender wide popular support.
In this election, you can throw exit polls out the window and pundits under the bus because ultimately it will boil down to people voting their hearts, and that's just beyond all precognition.