The OP’s “in/out” statement leads me to believe there is pitch coupling at KE… one reason why I recommendation a more neutral plane for learning aerobatics.

The “next step” depends upon what you enjoy. From your description, I’d say maybe your interest at the moment is sport aerobatics? If I’m wrong, correct me, but I’ll run with that until then. Without seeing you fly, I’ll make some assumptions about your professed skill level.

You have not learned all you can on the advanced trainers, but I’d say you are at a point where a more neutral plane will allow you to learn quicker. But, at the same time, you’ll get into trouble quicker too, so use caution. Neutral planes for the most part will do exactly what you command without too many naughties. This makes learning to fly aerobatics much easier without developing as many bad habits.

My suggestion is to look for a model that is designed to fly aerobatics well. This would mean a small pattern ship. Small pattern ships will be the most neutral flying plane in that size range you will ever fly. I’m thinking something like a Venus. Pattern ships are much easier to fly aerobatics with than a trainer, and they will be more neutral than a semi-scale aerobatic model or a fun fly type.