Glen, I had very successful treatment with LDR Brachytherapy. You can copy and paste my story from my signature. Having said that, I nor any of your other friends at HW can tell you if this is a good treatment for you. Dr. Stock has an excellent reputation and excellent experience. I suggest you contact him and specifically say you are worried about
urinary retention and ask him about
his concern in your particular case. There are no guarantees but a doc you trust will likely give you the straight scoop.
I have shown a couple of links below that may be helpful for your analysis and discussion with Dr. Stock. Note particularly the "indications" and "contra-indications" for LDR Brachy. The IPSS and prostate size are not totally predictive of urinary issues but can give you a good idea. If your prostate size is less than 60 CC and your IPSS is lower than 15-20 then that improves your chances of not having retention issues.
Hope this helps and good luck in your decision making.