It's hard to imagine how such a primitive suspension design could be as good as the dual link designs or even a high single pivot (eg. Orange). It's nothing to with the flex stays really, it's more to do with the pivot location. An Orange is a pretty primitive single pivot, but the pivot forward and above of the BB gives a much better rear axle path.
The speci faux-bar design places huge demands on the shock to fill the gaps left out by the lack of good kinematics. I'm all for saving weight where it makes sense, but I just can't get enthused by a design like this.