Honestly, I am intrigued by the concept of Nimble and other similar games, but my personal taste would be to eliminate the damage roll rather than the attack one.
I don't like all of the stuff DC20 does, but to my tastes, "Just make one d20-based roll to determine both if you succeed AND how well."
I can't tell you how often I have watched the enthusiasm deflate from my table when "I got a 23: solid hit!" is then followed by "And 4 damage."
And I just can't get excited by "All but 1/Xth of attacks hit." It would feel like you're hitting ALL the time. As Professor DM put it in his rabbit hole video years ago: "Having to roll between a 6 and 13 to hit just FEELS right."