I'll go all "anal vintage homo" here...
The volute is only 1/3 the equation with the Norlin headstocks. In 1969 Norlin instituted a lot of changes in Gibson and Les Pauls in particular. First, the size of the headstock. I think the big 70s style paddle is gaudy. It's about as graceful and elegant as a lime green leisure suit with white stitching.
Secondly, the pitch of the headstock was reduced from 17 degrees to 14. (or was it 14 to 12- I forget) Practically, it reduces stress on the area around the nut, so it's ostensibly stronger there. But it also reduces the amount of downward thrust onto the nut. For whatever that's worth...
Then there's the volute.
I'm not in the repair business, but I've seen about as many headstock casualties from both voluted and non-voluted Gibsons... There are those that say the stress that's relieved directly behind the nut is transferred higher onto the headstock, and if you look at the breaks, that's where you see them.