In my 20 plus years of flying I've never found an easier nitro aerobatic trainer,
Sure, the Twist is good if you want to learn aerobatics.
IMO the person who has just got past the stage of learning to fly solo with a high-wing (most of them with generoud Dihedral) trainer and is looking for his first low-wing plane is not yet ready for a plane that is designed for full aerobatics.
The question in the OP of this thread was what is a good plane after a trainer, and I dont think that the Twist or any other full aerobatic plane is suitable.
A suitable plane would be with a low-wing, low wing loading, some dihedral and a non-simetric airfoil shaped wing. this will allow it to be flown relatively slow without risking a stall yet will be possible to do a fair degree of aerobatics once the pilot becomes familiar and confident with it.
As an example, google the Hangar-9 Pulse 60. any similar plane would be suitable.