Of course the IDF benefits. The kids leave the death camps with unsurpassable righteous indignation and the idea that somebody must pay for the Holocaust. The irony of the visits to the death camps, built by the ultimate militarist state, is that they promote militarism. Please see the movie "Defamation" to see the psychology of the trip to the death camps in action. Whatever the effect on the kids, the IDF doesn't need a boost in home support, but it sorely needs a boost in the reputation it has earned for itself worldwide through actual deeds in the occupied territories as shown on so many video tapes and still photos.
Second rocket fired from Gaza explodes inside Strip (Haaretz)
from the article: Poland trips boost Israeli students’ opinions of the IDF, study finds