My heart goes out to you and your husband.
Your particular situation requires the very best counsel in the country--you have a far more challenging case than most who post here. I doubt that you will find better counsel than Scardino or Dr. Eastham at MSK.
One of my prostate cancer mentors went to Seattle, about 9 years ago, for brachytherapy. He raves about the quality of treatment he received there. If you go that route (brachy) or brachy with external beam, you're in a city with some of the best in the world.
As I have explored and researched various options I have found great variation in how various doctors view the best treatment options. Where I live there is only one hospital that has a davinci robot--few surgeons have experience, and fewer still are up the learning curve to the point where they're really reliable. Now I've heard that another hospital will be getting a davinci, so we can expect more public acceptance and understanding throughout the medical community of this treatment option.
I seem to be rambling, and I'm sorry. The point I'm trying to make is, using the davinci robot option as an example, that many doctors do not know very much about things outside their direct area of experience. This is understandable. Surgeons prefer and trust surgery, radiation oncologists will counsel their treatment approaches. All of them will have a risk of side effects and no one can guarantee your results. The main thing is the skill and experience of the practitioner, whatever the specialty.
The aggressiveness of your tumor and specifics will require the greatest skill (I know I am stating the obvious). I would seek the counsel of the two or three top options in the country, Scardino at MSK, someone like Partin at John Hopkins, plus the advice of the top radiological oncologist in Seattle. Stick with the research until you are confident of your choice.
Oh, just thought of one more factor to consider, and that is that Scardino is one of the best and one of the few doctors who is doing nerve grafts. Most won't even touch this procedure. If it were me, I would be very interested in his views on the applicability of this for your situation...
Best of luck and you will be in my prayers.