@Joep Nice list and report. Have you considered Jace, Vryn's Prodigy alongside or in place of Snapcaster?
I have thought about it briefly, but never tested him out. The main reason is that right now the deck invalidates a lot of the removal opponents play as the creatures have already done their damage when they enter the battlefield. Jace, Vryn's Prodigy would change that and actively make any removal my opponent has good and worth fighting over, which means I'll be spending resources on a fight I would otherwise not have to.
On the other hand, the upside is pretty good. The looting does seem to be where I wanted to be with Dack, as drawing and discarding 1 or 2 cards is pretty much all I would need in this deck. The upside that it turns into another snapcaster is also awesome.
If I decide to play another planeswalker, this might just hit the sweet spot in terms of upside. I would not replace a snapcaster at this point, because those are too important with the Terminus package, and they also serve the role of surprise blocker. In addition, I run 2 Mental Missteps at this point, making Snapcaster a great addition.
That said, I am still a little hesistant given what I outlined earlier. Then again, it's a solid card that I might just give a spin to get a real feel for it other than theorizing over it.