I have to disagree with you, Mort: moving Burmi down to the 4th turns that line into a possible possession line that can spell off the other lines, but I think that it will not drive any offense. Let's say it's the 3rd period, and the Jets are behind - what happens to that line? It sits on the bench. Where does that put us? It gives us a 4th line that get 6-8 minutes again.
Burmi is a very good player - very strong on the possession side, but he does not drive offense. The book hasn't been written on Petan yet, and I think he'll be a very responsible player defensively and help drive possession, but we don't know that yet. We DO know that he can drive offense, unlike Burmi.
For me, that's why you place him on the 4th. Instead of overloading the 3rd and creating a weaker 4th, you balance the two lines. Stafford offsets the low scoring of Burmi and Lowry, Burmi and Lowry offset the relatively poor defensive play of Staff, allowing him to simply seek offense. Petan perks up the 4th, making them dangerous to put pucks in the net with more regularity than before. I think we'll see some good match-ups for them, especially at home - I think Petan - Copp - Thor could potentially feast on some of the weaker 4th lines out there.
As you state: injuries will happen - Petan will be forced to move up. Petan will also get PP2 time, I'm sure. In the meantime, I love the idea of 4 lines for an opposing coach to have to worry about.