Read my recent lengthy post on making a decision about treatments. I didn't have a Gleason 8 but a Gleason 3+4. So things, as you so aptly point out, truly are different for each of us. Here is what I understood from my research.
There seems to be mixed opinions amongst the medical community as to the efficacy of various treatments. Some believe that surgery is a failure if there are postive margins. That is because if you don't get all the cancer, you have to do other treatments. It is true that the higher the Gleason score or PSA, the higher the probability of having extracapsular extensions that result in positive surgical margins.
However, my surgeon, Dr. Catalona, feels that surgery is not necessarily a failure if you have positive margins. He feels that because there is less cancer post surgery adjuvant radiation treatment has a better chance of being successful. Dr. Catalona in Chicago is one of the top researchers of Prostate Cancer in the country. He alone has done over 5000 surgeries.
But also consider that you can have a higher Gleason score and end up with negative margins post surgery. Your PSA is not that high, so it may be indicative of the cancer still being organ confined. If the cancer is still contained within the gland, then you still have a better prognosis post surgery than if you have positive margins post surgery. In this case, I'm not sure if other treatments would be recommended or needed. Also, if you have Protons or IMRT and your PSA goes down nicely and you don't have subsequent rises in your PSA, you may also not need additional therapies. But I'm not 100% certain on this.
Also remember that all you know now is your clinical stage...which is what can be known of your cancer from your PSA and biopsy. Whether your cancer is still organ confined is what no one can tell you without having surgery. That to me is the "gamble" when you have surgery.
One thing the Radiation Oncologists say is a benefit with radiation as a primary treatment is that there is a margin around the prostate that is treated, and in particular if you have a higher Gleason score and PSA this can give the radiation a better chance of killing all the cancer even if it has escaped into the prostate bed.
Bottom line is that there are no guarantees with either surgery or radiation (Protons or IMRT or seed implants, etc.). With either there is still some chance that the cancer has spread to the lymph nodes or that a person has micrometastisis (systemic disease that is as of yet undetectable by bone or CT scans). If that is the case, then there is a risk that biochemical failure will occur post radiation or surgery (this is defined differently for surgery and radiation). When biochemical failure occurs, other treatments such as hormone therapy can be used if the disease is believed to be systemic vs. local or locally advanced (in the prostate bed). Or salvage radiation can be done post surgery or salvage cryosurgery post radiation if the disease is still felt to be localized or locally advanced.
I guess there is also the option of not awaiting biochemical failure of either surgery or radiation to start Hormone Therapy. Again, I'm not as informed on this, as this was not yet my concern.
Maybe you know all this already. And maybe I'm wrong on some of it. I just wanted to share with you what I learned in case it might help you.