Spreader loads have been discussed for years on this forum. Many, especially hunters criticize them as a danger to the dogs in upland hunting situations. I've used RST Spread-Rs and Polywad doublewides enough to have some opinions.

They're useless past twenty yards because they spread too much to effectively kill anything and become a real danger to the bird dogs. Within twenty yards though they'll make a better shot of you as well as convert your tight choked guns into bird killers, and any bird dog shot with them is the hunter's fault for shooting too close to the dog or the dog jumping into the line of fire.

Good information on the history of these interesting alternative shotgun loads in this thread...Geo