I don't think that Knox and Sollecito were convicted based on their lying or behavior alone. It was the combination of the dishonesty and behavior with the more important forensic evidence.
Meredith's DNA was on the blade of the knife. The defense team alleges that this was a result of contamination, the prosecution disagrees. Raffaele's DNA was on the bra clasp. The defense team alleges again that this was a result of contamination. Essentially, the defense team has argued that all the incriminating DNA was a result of contamination, or incompetency, when it pertained to Knox and Sollecito. The problem with that argument, in part, is that the same team collected evidence in the same manner from the same crime scene at the same time for all three convicted persons. If the evidence implicated Rudy, everything was done correctly. If the evidence implicated Knox or Sollecito, then the defense position is that everything was done incorrectly. That just doesn't add up.