Hi Colin
Sorry to hear that the news was as you expected but not as you had hoped.
If it helps, my OH has had surgery to remove prostate. When he was diagnosed, we asked the surgeon what he would do with our set of results. He said he would go for the surgery. It's alswsys worth asking your consultant. They may not answer, but if they do it helps. Post surgery, the consultant said that he considered the decision was justified because the Gleason was 9 at pathology, and it had reached but not exceeded the surgical margin. On his biopsy, he only had 3% in one lobe and 18% in the other.
So the positive is that hopefully it was caught in time, and he is cured.
On the other hand, the side effects of the surgery have been very hard for him to deal with. Six months on he is dry at night but leaks like mad in the day. He can't drink beer. This is the end of life as we know it. He has little or no movement on the erection front, but it's early days. However, he is not a patient man, and is very distressed by it all. The side effects of the surgery were not adequately explained to him before surgery, although he would probably still have had it.
With a Gleason 6, you have the luxury of time to decide. But at the end of the day, you need to go with your gut feeling.