Hi Cav104,
It doesn't and shouldn't matter. I've never noticed any qualitative difference in bass frequencies based on the radiation pattern of the subwoofer driver. A sub is just pressurizing the air molecules in the room and how it does that, whether by means of an active driver, port, passive radiator, or internal or down-firing driver doesn't seem to influence the tonal quality, at least not in my experience.
Years ago, I built two very large coffin-like transmission-line top-firing passive subwoofers. I lived in a high-rise and it was the neighbor across the hall who used to pound on my door when I was letting things rip--not the apt dwellers upstairs or below me.
If you used an unusually high crossover frequency, say 90 or 100 Hz or higher, then differences might become apparent because bass starts to become directional at those frequencies.
Regards,
