PBL,
Repairing a duct with titanium rather than with stainless steel is not so related. Witness the people on this thread who think that the effect would have been the same with stainless steel, and witness the extensive experimentation conducted by the BEA under contract to show that it wasn't the same.
I think you misunderstood the BEA report regarding the significance of titanium vs. stainless steel. What I conclude from section 1.16.5 ("Tyre destruction mechanism", p. 97 in the English PDF version): For the low speed cutting tests they used one strip made of titanium, and some others made of "a stainless steel whose material strength characteristics are similar to titanium". For the high speed tests they used titanium only. But there is no hint that the low speed tests indicated a significant difference between the two materials. Yes, one strip was flattened instead of cutting into the tyre, but this was due to its positioning on the runway, and it happened to be the one made of titanium.