Quick comment on the Fantasy Flight narrative dice system---
It took me a couple of times of reading through the Genesys core mechanic section to fully grasp it, but once I understood the basic concept, it actually seemed quite elegant.
In truth, it's no more complex than d20---"Okay, so, I have +3 from proficiency, +3 from Strength, +1 from my magic sword, +1 for weapon focus, -1 because the enemy has some nifty defensive ability, oh, and I'm going to to a Power Attack for another -2, so, what's my bonus now? Oh, and I'm rolling with Advantage? . . . Okay, and my total is.....?"
Whereas in Genesys the conversation would be, "Okay, so I've got three ability dice and I've upgraded two to proficiency dice, against a Difficulty 2 maneuver (2 difficulty dice in the pool), with one Advantage die and one Disadvantage die." *rolls* "Okay cool, so I have a total of two success and and one threat."
The difference with the narrative dice system, the difficulty is already calculated in to the dice pool. You're never adding fiddly modifiers, you just adjust the dice pool and roll. When finished, check the success/failure and advantage/threat. I've not actually played with the Genesys system yet (though I'm planning to as soon as is viable), but I have the sense that the dice mechanic really won't be a problem after a session or two to get used to it.