It's the same system that we are constantly told is filled with liars, corruption and criminal incompetence that is conducting the appeal so on what rational basis can you say the convictions won't be upheld? Don't the police still have to save face? What will the Italian judiciary look like if the love birds are found not guilty? That can't be allowed to happen. What makes you think that Vecchiotti and Conti are any different than Stefanoni?
The appeal court is likely to be presented with a very different set of evidence and testimony to evaluate in the key areas. Already the first trial's "star witness", Curatolo, has been shown up for the pathetic drug addict/dealer, likely police stooge, and serial "misrememberer" that he is. And if the leaks in the Italian media are to be believed, the independent DNA experts are likely to say that the knife and the bra clasp are not only not testable, but also that Stefanoni's original testing techniques were bogus and inadmissible.
In addition to that, the defence teams will have got their act together and should be presenting a far stronger rebuttal against what remains of the prosecution's arguments. I would expect them to argue very strongly (and far more strongly than in the first trial) in areas such as computer evidence, mobile phone evidence and time of death.
So that's how the verdict in the first appeal may be one of not-guilty*. Additionally, I trust that Hellmann is a better reasoner than Massei, and also that the lay members of the judicial panel are more on the ball (they have to be educated to a higher standard than the lay jurors in the first trial). You're damn right that the police (and Mignini) will be desperately trying to save face, but I can't help thinking that the tide will go so strongly against them that it will be utterly overwhelming. And, in fact, I think that it would reflect well on the Italian judiciary if a not-guilty verdict is reached in the first appeal: not only will it vindicate the multi-trial system in place in Italy, but it will also show that Italian courts are capable of reaching just and fair decisions based on the evidence presented to them.
By the way, anything to say on the time of death debate, and the trial testimony of the various pathologists? You went curiously (and uncharacteristically) quiet after I posted the quotes from the Massei report....
* Incidentally, you're using incorrect nomenclature when you refer to "upholding convictions". You may be unaware of this fact, but the appeal trial is a de novo trial, in which the verdict of the first trial is not an issue. There is no conviction to "uphold" - indeed neither Knox nor Sollecito is actually convicted yet. They have been found guilty in the first trial. They will have to be found guilty in the first appeal and the Supreme Court appeal if they are to be convicted of murder. Just so you know......