I train, I was practicing BJJ up until I had to leave school for this quarter. I've had friends who've injured their knees and I gotta say it's been a bitch, it's really easy to injure yourself especially if you fall the wrong way. Your knee never really is quite the same but you can ease your pain and reduce injury if you wear a knee strap, one of my coaches from grecko roman wrestling back in the day had a horrible knee injury in a match that really affected him during the years, he used a knee strap to keep his knee steady and provide comfort when he fell, it did enough to the point that he was able to participate with us.
Go with the hamstrings but if you can get hamstrings from a donors body that's better.
Msg me if you're up for sparring sometime, don't get too many peeps who want to spar often.