The pilot reported that he was taking off on the grass runway with a tailwind of about 8 knots. After the airplane became airborne about midfield he had a question on climb performance and decided to abort the takeoff. During the abort, control was lost and the airplane flipped inverted resulting in substantial damage to the engine mount, lower fuselage, one wing and the vertical fin and rudder. He credited the four-point shoulder harness installation with saving him from injury. The pilot also reported that there was no preimpact malfunction or failure.