Cubic loading is becomming a popular BUZZ word, however dont place too much faith in it. It's good for rough comparison but buy no means does it mean that two planes with the same load will fly the same. For instance you could have two identical ex300's with the only difference being the shape and thickness of the airfoil, they will both have the same cubic load but fly very different. If the wing on your plane has a relitivly sharp leading edge it will stall more aggressivly, at a lower angle of attack and at a higher speed then a round leading edge, this will result in higher landing speeds. I have flown an AW Edge equiped with a 4-stroke and smoke at an all up weight over 9 lbs with no problems. The plane handled well with no noticable bad habbits. Sealing the hinge lines made a considerable improvement in control responce.