From the specs, the Naro servo looks to be a good servo, and the torque is a lot more than the HS 56. However, if everything is tight and bind free as it should be, there is more than enough torque from the HS 56, and I (personally) wouldn't be able to notice 2 1/100's of a second in speed over 60 degrees.
That said, I am still learning 3D flight with it and am still very much in the learning stages of inverted flight also.
What prompted me to go with the HS 56 over the 55's or anything else what the fact that there is (what feels like) zero slop in the gears. The servo is rock solid. With the exception of digital servo's, I have never had such precision, I love em!