How does wind affect the glider?
More mass or weight increases the inertia of the plane, which means the sane force of wind induces a smaller acceleration or chage of speed (side-side and up-down).
If the mass is centered, it will not change the reaction of the glider to wind-induced rolls, yaws and pitch changes.
Increased weight also forces the plane to fly faster in order to generate increased lift to compensate, increasing the stall speed some.