Hi David, I noted you've looked at the options so here is my experience although it got a bit rambling maybe.
As you may have read specialists often prefer their own type of treatment so if a radiologist recommends surgery it might be a strikingly honest opinion.
As others have said Gleason 6 is regarded as mild and one oncologist I watched on YouTube ummed and ahhed about it being 'cancer' at all. He thought Active Surveillance would be a preferred option unless there are other factors which I assumed meant it was in a risky position.
I only considered surgery as they said it was close to the edge and I wanted it out before it grew, it being a 4+3 from the biopsy (4+4 post surgery). I liked the idea of going to sleep and waking up with it done and just a healing process to complete. That's how it was although I have significant ED, but not complete. At the time radiotherapy and hormones sounded too long winded and at the time to me contained many risky uncertainties. Such as longer term radiotherapy effects and that hormones have unknown side effects changing how you think which I feared meant I wouldn't be me. Although nowadays, just 6yrs later, RT has improved precision.
I've found that 6yrs since the op have made me a bit more philosophical and knowledgeable about it, it looks like it's coming back. I also dont know if it's better to have a mind that thinks about sex but can't do a lot about it physically or a mind that doesn't think about sex and has no inclination to want to do anything about it. I prefer the former I think although the latter may be temporary so better in that case.
I've no regrets and it's rare to hear from anyone who regrets their choice. Usually there isn't a lot of difference in outcome although they say a younger man might have surgery as he can come back and have RT later if necessary. Someone with high gleason and suspect spread will likely do better with RT as they can aim outside the prostate.
You might ask the oncologist about Brachytherapy as well as beam radiotherapy. I don't know a lot about either. Although I hope Active Surveillance is enough. With my current knowledge I'd take that if I thought it was safe. You can always ask for treatment if you start to worry.
I hope that helps. Regards Peter