My husband opted for Brachytherapy because other options were not as viable. You are correct in the statistics show equal success rates with surgery at 15-20 years out. Surgery was riskier for him so we opted for Brachytherapy out of a Toronto, Ontario hospital. His implant was 91 seeds (stranded) with relatively little side effect (other than fatigue). His PSA scores are consistently dropping at every visit.
If you want to know more about Brachytherapy there is a post (JustJulie's Brachytherapy Journey) on this site - have a read, I tried to detail everything from the emotional roller coast to the actual procedure but if you have ANY other questions - just ask - I'm happy to help where I can.
As far as having young children, we have two who were 10 and 15 at the time of their father's diagnosis - do not exclude them from conversation - they need to know that the emotional roller coaster is not because of them - we included them in every stage of conversation.
Good luck to you in your decision making - ask anything you need to to help you make a confident decision.