I think the point is partially lost about why this concotion was brought to market. This stackable concept isn't designed to take the performance crown, although being competitive with the leading rads is an added benefit.

This is designed to squeeze more performance despite space constraints. Most people do not have a colossal case. For the average slim full tower case, there is a limited amount of radiator space. To a moderate degree, this stackable radiator concept helps add more radiator capacity for a seemingly maxed-out situation.

This is not revolutionary... its just evolutionary.