I fly mine with a 61SF and it flies well. I do fly from a paved runway surface but believe it would have not problem in a manicured grass strip. It was never weighed but I believe that it's in the middle of the range (8.5 or so). The airfoil on this model is fudged to provide more lift and better slow speed characteristics. I don't believe that some additional weight would cause the model to become a dog. In fact I think it would fly fine.