Square shot is not a new concept. It was developed over a hundred years ago for use in tightly or relatively tightly choked guns in the bocage region of France. The bocage is a very thick cover that offers only fleeting shots at departing gamebirds. The square shot was developed to open patterns quickly and was call dispersante (spreader). The shot was lead, the birds relatively frail and the range extremely close, thus any penetration issues didn't exist.
The problem with Blind Side, as I see it, is twofold. First, in order to get any range at all out of the load, the wad is designed to stay with the load for a longer period of time to suppress or retard the pattern bloom. High speed video shows this wad to stay with the shot for seven to 10 yards. From the patterning I've done with them (#2s, not #5s), even with the increased payload, you loose density for large ducks at 35 to 40 yards. And because of that wad, anything inside of 25 yards is hamburger if you center it. The other part of it is that the square (hex) shot, when measured on an equal basis with round shot, actually reduces penetration.
In my opinion, you can get twice the results with Xperts (which aren't top of the line) at half the price.
I feel slightly sorry for a man who has never patterned his gun, who has no idea how far his chosen load will retain killing penetration. But I'm extremely sorry for the ducks he shoots at beyond the killing range of his gun and load - Bob Brister