I think plastic pads make a horse even more sting-y. I use leather rim pads if the horse has a heel problem. When you use a wedge pad, you can see a really big difference in action between plastic and leather. We need a good leather wedge pad. I m using more leather pads that ever before.
Leather lets the foot breathe.
I do use rubber and plastic pads too, but they retain moisture, and they leave the foot hollow. I ve experimented with the new TAK pad, and with different packings. With the foot moving up and down. the right type of packing is important. It needs to be firm, to stabilize the foot. It is amazing what effect a small change can have on a problem horse.