Composite crown designs are far from new, as you know, and you are spot on as to the main reason why it is done. 12 grams seems a little light, to be honest, if that is all they save. We did a composite driver quite a few years ago and easily saved 20-25 grams from titanium crown. We also did a magnesium crown driver and saved close to 20 grams. Obviously how much is saved depends on how much composite is used. My feeling is any weight that be redistributed from areas that do not enhance performance to those that do is a plus. In a driver, at 200 grams, that 12 grams is 6 % of the weight. I think 10% or more is better and anything less, in my opinion, would make it difficult to see a measurable effect. Maybe it does, but a lot of very precise data collecting would need to be done to show the 6% weight re-distribution had a dramatic effect. That being said, and I’m repeating myself here, any weight you can re-distribute to areas in a driver (low, rearward, perimeter, etc.) that enhance performance is a good thing. The other thing that composite crowns have to offer is the affect it has on the sound. Composite absorbs vibrations differently and definitely can make a driver sound more appealing, unless you like the high pitched metal sound. Hope this helps.