This is really a tip for those who have the MSD or even other aftermarket coils in their cars. It will perform better with less aluminum to steel mixed in the ground path. Electricity always follows the path of least resistance. The bolts are not the necessarily the best path to ground. In my case the aluminum standoffs that came with the coil have rust bonded to the end of them from the dis similar metals eating each other.
Providing a good ground for anything in the cars of today is a must. You said the coil was operating without being grounded and if you think about it the power/control plug was providing the ground and is probably not what you want.
They are worth it if installed correctly. It is a slight improvement likely due to the better spark plug leads used with this coil. You can however purchase the 8.5mm superconductor wires for the stock coil MSD 32949 to yield the same results.