I had a FF string on an old "zipper". The overlays were wood and fiberglass. I was getting cracking around the top. Bill Dunn, said FF did it. It confused me. I told him I shot well over 3-4K shots with FF on that bow. He said I was lucky. I ended up grinding off the wood/glass, and putting phenolic on.

I myself don't see how padded ff can cut thru a lam.