I looked into getting one of these when I was looking for a 4 blade prop, and decided to go ahead and spend the extra money for Stainless Steel because of what I had read about them. They are good props, and certainly cheaper than SST, but they are composite material, and therefore subject to flexing. Weighting down the boat for boarding does increase the stress of the prop when starting out, and the composite material flexes some causing stress to the blades. As you can see above, Bobby suspects this on his.
That being said, they are cheaper than SST by about half. If you do hit something and break a blade, you can replace it, versus the entire prop, or having repair work done on a SST. You can also order extar blades of different pitch to try out and see what works best.
Not trying to convince you for them or against them, just providing a little insight as to why I shelled out the $300 for a SST instead of getting the composite.