Your surgeon sounds optimistic to me. My own experience was very positive. I got most of my function back but I had 3 friends who can not have erections without hardware. All of the surgeries were done robotic, by solid surgeons. I hate to present anecdotal evidence of this kind of thing. My experience might be very different than study results. Here is what John Hopkins has to say. https://www.hopkinsmedicine.org/health/conditions-and-diseases/prostate-cancer/erectile-dysfunction-after-prostate-cancer