I think Whigham said it best - Dungey is the QB Dino has to play and Devito is the QB Dino can't wait to play.
Dungey is no doubt the starter. But my unpopular, fearless prediction - Dino will look to give Devito the reigns as soon as he can without losing the locker room. I think if Dungey gets hurt and has to sit out a few games, and Devito does what Dino thinks he will while Dungey is out, that Dino will stick with Devito - basically a Bledsoe/Brady situation. I think if Dungey puts up another stinker like Miami, Dino will be willing to pull Dungey if Devito has shown prior success.
Dungey has been the guy and has earned the right to be the starter. He's been an absolutely flawless ambassador and representative for the school and is the benchmark for toughness, commitment, and competitiveness. He has the fierce and loyal devotion of many, and it is well earned.
But the problem is that he's not a particularly skilled QB, and he is particularly ill suited for what Dino is trying to do. Dino's system prioritizes accuracy and quick decision making. Dungey has consistently struggled with accuracy and continues to make bad decisions - he doesn't consistently go through his progressions, is too quick to leave the pocket and run, and once running is a reckless runner.
In the land of the blind the one eyed man is king. Dungey has benefitted tremendously from the appalling lack of QB talent before him (Hunt) and with him on the depth chart. He's been insanely valuable to Syracuse because he is a decent QB, and there has been a massive gap between decent and the other options Syracuse has had. Dino's system allows him to put up huge counting stats while the typical fan and media member ignores efficiency.
I think Devito is good, maybe even really good, and more importantly, has the attributes that makes Dino's system hum along. Right now the difference between decent and good isn't enough to justify the waves such a move would make in the locker room. But I genuinely believe as soon as Dino thinks he can get Devito in there without causing a massive distraction, he will do it.