I don't think playing "hits" are the issue. They're not suggesting they're just going to play hits sets. In fact, I suspect they won't. They're just saying they'll be sticking to the same set for a tour.
Also, having seen Mangini play, I honestly have no desire to see Portnoy back. Mangini was awesome.
27/4 Dan Patlansky
3/5 Maiden United
7/5 One Machine
8/5 Blaze Bayley