If two cup diameters are the same, the mouthpiece with the high point closer to the outside may feel larger. This will determine how wide the rim feels on your chops. A larger outside radius will make a narrow rim feel wider, especially in the upper register, where more mouthpiece pressure is experienced. This will give you more rim area on your chops if you add mouthpiece pressure. The rim is a very personal choice.
Careful experimentation is the key.
Try to change only one aspect of the rim at a time. Remember what works for you and keep notes. You must know what has worked for you in the past to move to the next level. GR Mouthpiece rims are designed for a smooth luxurious feel and enhanced endurance. You will feel a more positive grip and experience cleaner attacks due to a comfortable, yet defined bite.