In my circumstances, the Gleason score was about the same as your Dad's with a lower PSA. Given that the prostate was small, and the cancer was contained to the 'capsule'...no lumps or bumps or nothing outside of it, both my urologist and my oncologist found me to be a perfect candidate for the radioactive seeds (iodine 125). Though I have heard talk of side-effects kicking in 2 or 3 years down the road, that really doesn't make sense as the radioactivity is gone in 12 months. So far there are so few side effects going on for me that I feel guilty.
As to the pads...that is a dignity issue. Trust me, as this process goes on, you learn to leave your concept of dignity behind when you leave the house...cuz it only gets in the way...lol! Ask your mother about dignity with respect to childbirth...she'll understand the connection.
Thing is, that's ok though, because you soon learn that while this is all new and scary for your Dad (and y'all), you have a medical team that's good at what they do, care about all of you, nothing's new to them, and you learn to trust them. Unless there's a reason not to go for seeds, as a patient I'd recommend them. Which is to say, I'd do it all over again given the choices. Hope that helps more than it confuses the issue.