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.
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.