I don't see the harm in trying Galchenyuk with Pacioretty on the PP for a game or two.
Agreed. Gionta, Desharnais, and to a lesser extent Gallagher don't really produce on the PP. Gallagher is a little more valuable because of his willingness to stand in front of the net (Desharnais used to do that a lot more, but Gallagher has become the man to do that).
Desharnais deserves his ES ice-time. He's one of the top-5 producers on the time at ES. But that line needs to figure out a way to stop being scored on so much. I'm sure part of it is bad-luck, but part of it is also that all three are usually caught too far up the ice.