Thanks so much for all the great information. We would be very inclined to keep him and give him a try. He is so sweet and beautiful. But we do have fussy neighbors who are good friends who also are our chicken-sitters when we are away, which is often. They have their small grandchildren with them often too and are strongly opposed to roosters. So, to be nice, we will continue to find a home for him. I think there will be tears when he goes.
Are your birds behind a fence at all? I have small kids and multiple roosters, but our hens are pastured and my kids know better than to go into the chicken pasture alone. I will say that I've had, oh, gosh, 30+ roosters so far, and only maybe three were culled for aggression.
Sorry about your having to get rid of him. I'm glad you took the chance to pick up an abandoned chicken.