I second shortening the cape. It gives him a better silhouette and further distinguishes him the previous iteration.
Some slight tweaks here or there. I’m fine with the material. Maybe tone down the lines a bit, but don’t get rid of them. They give the suit the illusion of muscle definition and without them the suit just looks flat and weird. Also disagree on making it more skin tight. The slight bagginess and looseness feels more utilitarian and makes him look more approachable. Same with the collar. Without it, this version of the suit just looks wrong. I have yet to see an argument against it other than “I don’t like it.”
Other than that, I wouldn’t change anything else. I trust James Gunn with whatever he decides to do with it on the next film.