Just ran into Givony's writeup of Dunn's workout vs Elfrid Payton. Very similar to Chad Ford's FWIW:
Dunn, at 6-foot-4, showed he can step into an NBA game and have a positive impact on the defensive end. He’s likely the best on-the-ball defender in this draft and can check both guard spots. He played with a mean streak in one-on-one and two-on-two competition and proved that he’s not a non-shooter. Payton matched his intensity and didn't give Dunn an inch on either end of the floor, which made for an extremely competitive workout. Payton's body and shooting stroke look to be making strides, and at 22 years old his future with the Magic is still promising.