Treatment options offered you are interesting. I was diagnosed with locally advanced PCa April last year: G8, T3a, PSA 5.2 M0 N1 - limited spread to local lymph nodes. The NHS offered me curative intent treatment comprising HT + IMRT (74 Gy over 37 sessions). I took a second opinion privately from a surgeon who specialises in robotic RP. His view was that in my case there was little to choose in terms of outcome between the 2 options. He emphasised that I should consider quality of life risks associated with the alternatives. I decided on the HT/RT route.
Obviously, your first option has the risks of both RP and RT. Have you been advised whether the RP procedure would be nerve sparing? As for RT, I was advised that it has a significant risk of impotence and a low risk of incontinence. What I didn't know was that the planned RT would include treatment to the seminal vesicles (which hadn't been shown to be affected by cancer), the effect of which is permanent sterility - an elaborate vasectomy! BTW, this didn't trouble me.
Your second option includes HT which has its own risks. I've been treated with HT for the last 12 months with side effects limited to minor hot flushes. Some others have worse experiences. I think that long term HT makes attention to fitness and diet a must, there being risks of muscle and bone wastage among others which makes It important to know how long you might be on HT.
While it's early days, the HT/RT combination (described by my oncology as the "gold standard" for cases like mine), has resulted in a good response by my body. Had there been a clear-cut advantage for RP I might well have taken that route.
As you'll read on here and hear from doctors, all cases are different. I suggest that you review with your doctors the risks and benefits of each treatment option: setting it out in a tabular form might help. You could also consider taking a second opinion - this won't offend your doctors and doesn't cost much. If you take this route, ensure that the second opinion doctor had access to scans, test results and notes.