Maybe slow isn't the right word for Ekholm, but in their one game together vs. f'ing
Anaheim the two of them struggled to limit the Ducks' open ice and stop them from getting in behind them (0:45, 1:16, 2:35 being good examples...). Though I do think that's a Ceci issue, as Ekholm with a slow boots Bouchard doesn't have the same issue.
Imo Ceci has the same issues you described for Nurse "
too aggressive/overreactive. Takes himself out of position too often. He also seems to puck watch a little too much for my liking." It feels like he's yet to meet a pinch/step up in the neutral zone that he didn't like this season (Again, see 0:45, 1:16, 2:35 in the video above...). Mix that in with his slowness getting back and it's a recipe for trouble.
For now I'm curious to see Nurse-Vinny and Kulak-Ceci for a few games. But if Vinny can't handle the top 4 minutes, it's going to come down to whom Kulak looked better playing with: Vinny or Ceci. With the loser sitting.
It's not so much because I think Stecher is amazing. Rather I'm leaning on Ekholm-Boucahrd and Kulak-Vinny/Ceci being such strong pairings, that Nurse can cover for a #5/6, whose style meshes well with him.