Eyes deceive. I don't trust other people's impressions, just the cold, hard facts.
There's a lot of literature about framing, that your preconceived notions determine what you observe.
I prefer Manning over MacDonald or Ghost on the PK, because he's more physical, and is more effective on crowded ice.
I prefer MacDonald over Manning at ES, because MacDonald is competent if not skilled, especially the further from his own net (he's good at blocking shots but not at clearing the crease). Manning gets lost in space, he's just not a good skater.
Both are limited, as are practically every 3rd pair D-man in the league (and some 2nd pair, as we've seen in past seasons).
However, don't take preseason performances too seriously, what a young D-man can get away with against scrubs can look a lot worse against real players. That's why I expect them to be gradually worked into the lineup, the same way Vorobyev and Lindblom will start against AHL competition on NA ice, and if they perform, they'll get called up at some point.
As I said before the season, the lineup in January may look very different than the one in October.