Surely it's more down to using the correct bore sizing and installation than the metallurgy of the pistons? It's not as if there is only a few cars in and out of the cosworth world using them.
After all if you've built the engine yourself, you're hardly likely to blame yourself for failure and on the other hand if your engine is professionally built and either fails or is noisy, what is going to be blamed? Workmanship or material failure?