Whenever possible, you want to shift any and all items to get the CG to the proper position on a plane, whether that means you need to remount the servos, add a box to move the battery, whatever. After all, dead weight is just that - dead. But if you have repositioned everything as much as possible, add weight as far forward or as far aft as physically possible, to reduce the amount of weight required. btw, a piece of lead stuck to the nose of the plane won't be visible from 40 feet away.