Onkyo 607 and "Double Bass" Feature

[Kali157]

Hello all. I just got my Emp Tek E5Ti tower speakers. Well, I got them over a week ago, but my wife and I were out of town. Anyway, ran Audyssey and it predictably set the fronts to full band. I set my center to 80Hz, my surrounds to 90 Hz, and my sub to 100Hz. Then I noticed a feature of Double Bass. This is the explanation according to Onkyo:

"With the Double Bass function, you can boost bass output by feeding bass sounds from the front left and right channels to the subwoofer... Double Bass function on. Bass from the front left and right channels is also fed to the subwoofer (default)."

So if I use this when my fronts are at full band, anything bellow 100Hz for the fronts will ALSO be sent to the sub as well, correct? I just want to make sure that I read that right. I would love to use the full band of my new fronts but keep the support of the sub. Any reason why I should keep this off and turn my fronts down to 80Hz?

Btw, I am listening to music with the E5Tis and I am REALLY enjoying them. Very nice sound.