There are two major limitations.... Can you please elaborate and provide supporting evidence that GB is limiting? ....
First, it seems to be very hard for some people to visualize the ghost ball. Maybe it's just a matter of more practice. To the extent that I use the ghost ball it is more a "feeling of fullness" than an image of a ball appearing next to the object ball. I think Joe Davis used the same method.
Second, the simplest ghost ball idea -- lining up the centers to the center of the pocket -- is wrong because of throw. That has to be compensated either by feel or subconsciously or with an explicit correction. What I call the "compensated ghost ball" moves the ghost ball slightly to adjust for the expected throw. By its definition, the compensated ghost ball is exact.