The advantage of being from a neighboring state

The advantage of being from a neighboring state is that a candidate is likely to be highly familiar to the voters.

But that is really only an advantage if those voters are less familiar with the other candidate(s). So sure, Bernie may be more well known in NH than he is in many other states, but come on, does anyone think these voters are not equally familiar with Hillary?

And as pointed out elsewhere, the states themselves are quite different, NH is a notably more conservative state than VT.

So for the Clinton side to talk about any kind of "home field advantage" for Sanders, it would seem to come down to, "Hey, if they know my opponent as well as they know me, it's not surprising that they would prefer him."

If Hillary was counting on name recognition to put this nomination in the bag, that may get harder... if Sanders keeps going as he has been lately, he should be on the verge of getting a whole lot more national name recognition.