I have a mixed flock and yes some heavy slow white ones as well and they are pets. While I would hate to lose any I think the benefits of happy chickens, healthier eggs and less feed bills outweighs the risk at this point. Of course if something takes my favorites Ill be singing an entirely different tuneGreat area for free ranging. For the chickens you don't have to clean it. You probably have a chicken missing from time to time if there are predators. But we can't predict if or how many losses you will have.
I had no losses at all in the past 5+ years, letting my small chickens free range a couple of hours during the day. I keep them locked up in a coop with secure run at night. In the morning they are free to step into a descent run with netting on top through a pop door with a chicken guard. When I am around the house i open the run door to let them free range.
My chickens flee when they see a dog and seem to know a neigbor cat is not a danger for them. They are good in hiding and can fly a bit. We don't have many predators here that hunt during the day. Just a fox now and then, and also hawks are spotted not far from here. But I always check if they get home because I know there is a risk when they don't come home.
If you choose to let them free range its important to choose a breed thats fit for this task. -> not white, heavy or pet chickens.