The 8340 SAM har a lower crossover frequency than the older 8040b, - 2,6 kHz vs 3 kHz . Probably also a steeper crossover, but Im not sure. This is good for directivity.One of the reasons I had bought them was also that the directivity was smoother than on its more expensive 8040B sibling:
It seems they fixed those issues though on its latest GLM variant 8340A:
View attachment 224528
The smaller 0,75 inch dome used in 8040b, 8030c and 8340 has slightly better dispersion over 10 KHz compared to the 1 inch tweeter in a040, and the 0,75 inch dome dont have the distortion breakups at 96 dB, so its a matter of swings and roundabouts.
Compromises, as in all two way loudspeakers.