There's really no need to go the trainer route since you've already gotten competent on the little T-28. If anything, you'll find that bigger planes are easier to fly in many ways. They aren't affected by the wind as much, they are easier to see, and their control response is smoother. The bigger T-28 foamy would be a sensible step for you, and it can do basic aerobatics. I love Sticks for a general purpose sport plane in any size also. They handle the wind very well and are extremely forgiving, yet can do any aerobatic maneuver you can think of besides snaps and spins.