Thanks. My only real experience with this stuff is in car audio. Generally, imaging cues start around 150hz. It's usually said that you can't localize frequencies below 80hz. However, I believe that this is only true in an anechoic chamber, or theater where absolutely nothing resonates at all. Maybe it's just because I'm thinking about it, but I can localize tones much lower by the pressure difference in the air.
Anyway, in a car it's rare to have a driver on axis, but it's still possible to get good imaging, midbass punch, etc. Of course that's a much smaller volume to pressurize. Anyway, I'm hoping someone who owns the 606s can comment.
If the 8" woofer only plays up to 150hz, that's well before it will start to beam, so the sound it produces should be omnidirectional. I don't know if that also applies to the punch in the chest kind of impact.