The only rolls I plan to hide are opposing checks where a level of suspense would be appreciated, and when I fear that player/character knowledge separation would be an issue to the continuation of the scene.

The PC is trying to lie to a guard to get past. He rolls his half of the dice pool in the open. I roll mine behind my screen.

One time, his roll crushes mine, and the guard completely believes him and lets the past with no incident.

Another time, I destroy his roll with a despair. The guard pretends to believe him and go with him, then radios his buddies to set up an ambush right where they are.

That adds a layer of suspense that i think can really be appreciated.

But like, for most rolls, like all combat rolls, skill checks, or many other things, I'll just let the rolls be in the open. The only thing that will make me want to hide rolls is diplomatic relations with NPCs. That way, they won't know how well they are doing just by the dice roll.

I have come to term this new dice mechanic and role playing game as "Co-op GMing". That's why I see no rhyme or reason to be hiding dice rolls behind a screen. Most rolls I encourage the players to make so they own the roll and what result it may bear. Keeping in mind Jay's statement, "the player is taking a social contract when he/she picks up that pool of dice."

Though as GM I still decide what Threat or Despair narratively means when they roll the dice. They can have fun with the advantage and Triumphs.

Find that the game moves so quickly that we can get so much done in an evening. DnD would be a slog fest with one encounter lasting all night. Had 4 encounters in the last session, not to mention the plethora of social interactions and role playing.

Keep the dice open, there is really no reason to conceal dice rolls as GM.