i bred them for one season and then sold my small flock, i really disliked their personalities, they were very flighty, and despite having a 20X20 run the hens were constantly picking on each other. I started with a mature m/f pair and added 2 mature hens, the 2 new hens relentlessly picked on the existing hen, to the point i had to separate her because she couldnt leave the perch or she would be mauled. later that year i tired to add 3 new grown pullets and when i went out a few hours after introduction i found they had ripped the head open on one and i had to put her down it was so bad. Thought beautiful i will never deal with sebrights again. the hens are downright nasty in my experiance.
ETA: the one mature hen i had to remove from the pen because the other two picked on her, i put in a communal bantam pen, several cockerals and a bunch of pullets/hens, she ruled the coop with a cast iron fist, i ended up having to re-home her to a free-range flock because she was such a nasty bird.