I think they're great!
I did pretty much the same things you did. Extra protein, extra perches, toys, space, you name it. It was not a lack of protein. Whatever reason started it, it became a habit, and most of my nine were pecking each other. There was one who was so scared, she spent almost all her time up on the roost, and only came down to eat and drink when the others were not in the coop. Those I spoke to about pinless peepers would act as though it was not a great idea, and that I should think about it very carefully before I did anything like that. I don't know what they were thinking, but they (the peepers) have been a godsend to my flock. Some of the girls took it better than others, a few of them had tantrums when the peepers were applied, but things are peaceful now. One of the BR's and both RIR's occasionally lunge at the other birds, but the pecking is pretty much done. I wish I'd done it sooner.
One thing I will mention, is that we have two birds out of the nine that do not wear them. One of those, my little Dora, doesn't ever peck anyone. It's just not her nature. The other EE that doesn't wear one does peck occasionally, but we can't get the peeper to stay on her. for some reason, her beak/nostril shape is slightly different, and it won't stay put. She just gives her head a good shake and it flies off. We have tried another peeper on her with the same result, so I know it's not the peepers.
All that said, I think they are a great invention, and I would not hesitate to use them again. At this time I don't really know how long we will have them on the birds, but it's been a month or more, and so far, so good.
