I had a spinner explode on me once while testing an engine in my garage. The spinner was brand new and had come with an ARF I was building. I concluded that the spinner backplate must have either had a hairline crack or been molded poorly as the backplate was the only piece broken. Since then I have only used aluminum backplate spinners as I feel they are much safer. The way I look at it, if you are going to skimp on something why risk hurting yourself or someone else while doing it.