southern touch99 has it right. Weight is the enemy of performance. By all means try to balance the airplane by moving stuff as much as possible. However for a finished aircraft, if only a small amount of weight is required for balance, go ahead and add it. One ounce represents less than 1% weight increase for a 7 pound aircraft. This will raise the stall speed by about one percent and I doubt if the performance loss can be noticed. This might be more practical than reworking the equipment installation.