Yes there are some balanced light weights and neck diving heavy weights without a doubt. The center of gravity is largely dependant on where the strap buttons are located along with other factors such as hardware, wood type, etc. I have never played an SG style that balanced well. But generally if you take two similar styled basses like a Jazz or P, heavier ones balance a little better IME.
But balance is only part of my issue with light weights. Part of my issue with light weight basses is that they don't stay put and they move around on me. Heavier basses anchor down and stay where I put them.
The perfect balance between weight, size and balance is my old Steinberger. And it stays where I put it even if I move around. The only think that I don't like about it is the narrower string spacing at the bridge compared to my J's and the high-fi sound.
The only correct answer is that there are so many factors too consider that there is no "right" answer for everyone. It all boils down to what you feel comfortale with and what works with your style.
Plus I have a different persective, I played tuba for many years and a bass like my Aria at 11 pounds is much lighter that a 35 to 45 pound sousaphone. And I have played 3 plus hours with that thing.
I have my doubts if Gibson understands balance on a bass.
Lighter bodies with a reasonable top horn often balance. Where a lot of Fender style basses have problems is using a light body and incredibly dense neck. While basswood and poplar are economical lighter body woods, most will still use Canadian rock maple for the neck, which is also economical but often quite heavy.
All around, an inline headstock adds more weight and changes the point of balance, too. A compact headstock can not only reduce overall weight, but also makes it easier to balance the bass as well.
