I don't think there is a breed of geese where you will not encounter aggression during breeding season. My gander won't attack me,. but he will grab the pantlegs of my hubby and goes nuts if a stranger comes near where the goose is during breeding season.
I only had him get me good once, it was last year. I let them incubate a late clutch and I was down at the barn to check on them and do some chores. I didn't see the gander but assumed he was off grazing. Walked into the barn, saw the goose, then saw a head pop out from under her wing. At almost the exact same moment he grabbed my leg (I was in shorts, it was late June) from behind and started walloping on me. When I leaned over to restrain him, he got my arms a couple times before I was able to grab him. I had a few bruises and some marks, but not much worse for the wear.
Because of where they were I took the goslings away, and within a half an hour of removing the goslings he was acting sweet as pie again. When the goslings were a couple weeks old and I felt they weren't going to be easily predated upon I began to let them out in a pen with a lamp. The goose was very interested and wouldn't leave the side of the pen, so I let her in with them and she acted as though they had never been apart. It worked out well in that other than the first couple weeks, they were out grazing under careful supervision of the goose and gander. They grew well on pasture with minor supplementation with commercial feed (supplemented with Niacin).
I like the Buffs, but I am going to be selling my flock within the next year as I replace them with a larger breed.