Why would you need a plastic wing for durability? We are racing on road here. Not 1/8 off road buggy. Hell even 1/10 off road uses lexan.

That wing provides absolutely no advantage over a lexan wing at 10mm.

It puts excess weight at the farthest point from center of balance and center of gravity. The amount of aerodynamic drag created most likely far exceeds the advantage of any additional down force. Any additional downforce created over the 10mm lexan wing most likley unbalanced the front downforce causing instability on high speed straights and corners.