Doug,
I just faced the same decision. I am almost 70, in good health except for periodic AFIB, and working full time as a technology consultant working mostly from home. After consulting with several other doctors I also went to Mayo Phoenix and they had me talk to focal, radiation and surgery specialists to help me make my own decision.

I believe the "right" decision may be different for others but mine was easy. My cancer was in two many separate locations in the prostate for focal. I really liked the radiation specialist but he told me my age and AFIB dictated radiation rather than surgery. The surgeon felt age and AFIB were not a significant issue. Things I considered (that the non-Mayo doctors never told me):
1) Once you have radiation you will not heal well which can lead serious complications if radiation does not kill all the cancer. (which does happen!)
2) Once you have radiation if you later have urinary problems (such as constant urges and low bladder capacity) any surgery to correct is HIGH risk.
3) The radiation path is a much longer journey than Robotic Proctectomy and includes multiple surgeries and surgery recovery period vs a single but more complex surgery.

Others might be different but for me radiation meant 1) a surgery to "scrape" the prostate to improve urination, 2) 2 to 3 months recovery from surgery, 3) Minor surgery to place markers and hydrogel spacer to block radiation from my colon/rectum. 3) 28 days of radiation treatment, and a single Hormone shot. 4) minor surgeries to remove hydrogel spacer once they were sure no more radiation is required.

If I was younger and more concerned about short-medium sexual function I might have taken a different path but for me I picked surgery which will only require a single recover period who many say is 2-3 weeks but my doctor will request 4-6 weeks from my employer.

Hope this is helpful . . wish you the best on selecting and making your journey.