Generally when you sit above the tweeter axis, assuming it has good dispersion you end up with a large hole in the crossover region (2-3K generally). This doesn't exist if you get a coaxial speaker.
Good example is the M106 once you go above axis: https://www.stereophile.com/images/914Revelfig5.jpg
Good example is the M106 once you go above axis: https://www.stereophile.com/images/914Revelfig5.jpg