I was 56 when diagnosed as well, most likely contained in the prostate. I checked into both and each treatment path claimed to be equally suited to yield success. After a lot of reading and discussion with physicians, I chose surgery for 2 reasons: 1) at my age the long term effects of radiation could be problematic later and 2) as noted previously here, surgery is very difficult and less successful post radiation. Whereas if you have surgery and pathology shows it isn't contained to prostate, radiation is still an option. There isn't a single right answer for everyone so ask a lot of questions and do your homework to make the best choice for you.
I just passed 9 month post surgery and I am comfortable I made the right decision for me. I use a pad for security but other that physical stress, excessive volume of fluids, and alcohol (LOL), I am usually pretty well controlled. Continence recovery has been a process for sure, and continues to be something I work at every day. I'm impatient but doing well and still improving despite rumors that the 1st 6 months is where it ends. Some people do great at 3-4 months and others need more time, there are many factors that affect every recovery, but I have found personally and in speaking to others, that the best results come from persistence
Good luck with your ultimate decision and your own journey!