You're talking about an axial roll right? where you simply jam the aileron stick to one side and hang on, right?

Is it not rolling fast enough or is it not holding it's heading well enough?

Have you tried rolls in both directions? Does it roll faster in one direction than it does in the other?

First off, the 4* is advertised just as you've noticed, as a good low wing trainer that does decent aerobatics. The Twist isn't a trainer; it's designed to be thrashed about. A trainer usually has design features that cause it to try to fly upright and straight. Those features cause the trainer to fight aerobatics. When a trainer is said to be a good 2nd plane, they're telling you that it is less trainer than the primary ones. So it fights less, but will still resist somewhat. The Twist is neither a primary or 2nd trainer. So the Twist isn't fighting at all.

I've been helping a friend fly his 4* and have noticed a couple of things. Those large, square wings really get bumped around by gusts. The plane doesn't pitch up or down, it does little roll bumps all the time. And it brings itself back level. I'd suggest that the plane looks like it's rolling along on a gravel road that has potholes. And it's like the buddies 4* has harder springs and shocks than my CAP for example.

It just might be that your 4* is doing what it's designed to do. The Twist certainly is.

On the other hand, almost every model can be improved. So........ Is it not rolling fast enough or is it not holding it's heading well enough? Have you tried rolls in both directions? Does it roll faster in one direction than it does in the other?