Back to the subject. The solution to neck dive lies where it always has - on the designer's drawing board. If he can't calculate a centre of gravity and place it properly, he shouldn't be in the job.
You know, that brings up an interesting point. I wonder if the earliest versions on th SG were better balanced and at some point slight changes were made which inadvertently shifted the center of gravity toward the head side.
Thinner bodies, heavier tuners, larger heads, etc. Many slight changes over the years could be the collective culprit.