The elevons will be getting the 9g servos this time and a slightly smaller surface with way more throw should be more reactive at any angle and speed. Those are the biggest control surfaces I have seen on any plane, elevon or not, and I have flown others which roll and pitch faster then that, For example the Baby Blender. Plus the angle the hinge line is at will be a bit of an advantage to leverage the air flow quicker along the TE of the control surface, that's my theory anyway.
Did you check out
@Tonero311 rudder servo set up on his posts, brilliant stuff, push/pull system from the center. And tis guy has a punisher skull in his avatar, cool dude in my books man. How are you going to make the elevons larger?