An ounce or two difference won't matter much on a big heavy plane, but on a small light plane it makes a HUGE difference. I'll go for lighter every time, even if it means the plane is fragile. Just a personal choice. There are plenty of planes out there that are designed to be reasonably durable, but precious few that are made for ultimate flight performance at the expense of everything else. It sounds like the E3D is one of those few.