I don't go out of my way to build light, especially with the bigger airplanes. They can carry much more weight with little effect. In fact I think the big planes in some instances can be too light. If a contest plane, I think it may be beneficial to have some method of adding ballast for windy conditions. Lightness has become much more of the rage now, then it was back in the 70s and 80s. We attempted to build as light as we could then, to a point. The point being the airframe had to withstand the higher normal speeds flown. Airplanes flew on their wings, not on their props, like many do today. Excepting of course R/C sailplanes, which since the beginning flew better if light. Again, Look at the end use and build accordingly.