CG is much easier to locate when dealing with a kit or plans built plane because they show a datum line where measurements are taken from. When dealing with an ARF this line isn't often shown so you are given a spot that they tell you that you should balance at this point. That's fine except you are left to wonder how the plane is to sit when in balance. When given a datum line it is easy to tell when the plane is at the correct level. I have built several Cubs but as john pointed out, they are not all the same. You can usually tell by the stab but I have only had to CG the kits, an ARF can be a mystery due to the lack of information given on there instructions.