Removing the dihedral will greatly reduce the ability to self correct back to level flying. But it won't make it respond more strongly to the aileron controls. So while it may not try to fight you to return to upright and level it will only be more responsive if you also increase the amount of aileron throw.

You might try another option that does not require you to modify the model. What you can do is move the CG back a little to make it handle with less tendency to recover in pitch. That will sharpen up the elevator response even without altering the amount of elevator throw.

For rolling maneuvers you can use aileron with rudder at the same time to really speed up and sharpen up the roll response. In this case the rudder and dihedral work with the ailerons and the results can be quite amazing and startling. Using the two controls together makes the rolls look more like snap rolls. Yet when you use one or the other by themselves you still have the softer almost training like response.

To aid in making a flat bottom wing fly better inverted you can reflex the ailerons upwards about 5°. It will make the model fly a little faster upright and not slow down as well for landing. But it makes it so with a rearward CG trim you can fly a flat bottom wing upside down quite well.

Try it. The results will almost certainly surprise you. And all without the need to do any big wing modifications.

The bench time you save can then be put into buying and setting up a more seriously aerobatic sport model.