I don't see Blow Up as a thriller--more of an existential or epistemological parable. I haven't seen Blow Out (or Blow Up) in a zillion years, but I don't think de Palma is trying to pull the rug out from under the audience (as Antonioni was--or Cronenberg was in eXistenZ, for example). My overall assessment of de Palma is that he's a good director but a little too preoccpied with self-consciousness to be a great director (which is why Obsession is inferior to Vertigo, or Dressed to Kill is inferior to Psycho). So Blow Up / Blow Out are more apples and oranges than the other two. The two Scarfaces would be a better example--here De Palma's remake stands on its own (though I do prefer the original, in spite of Pacino's over-the-top performance).