I went to see the doctor today. He said there might be a 20% chance that men with undiscovered testicles get cancer than a man with 2 balls. He also said my new ball will not increase sperm. They will be no sperm and hormones will stay the same. Also the size might be different. If the size is different it might be uncomfortable. So if that's the case they might take it out all together. And there is an option to replace with a plastic ball.
But saying that he reccomend I have it done.