I assume crossing at 1200-1400Hz, where the wavelength is still smaller than the distance (center to center, this applies e.g. for 15" as well, crossing point 800-900Hz ), so the drivers will be in phase.
I am not sure why one should use significantly assymetrical wg when you are limited by the smaller dimension anyway. I assume when horizontally aligned, there will unevitably be an unewen power response vertically (the woofer is circular).
I wouldn't say they have a hole, but they should not be listened at 0° but rather a couple of degrees off (so the crossover should be adapted to a flat response at let's say 15°). I guess you can partially improve it with an appropriate foam in the mouth though.