In my X5's particular application the answer is yes.
To start with I have an open floor plan with the living room itself larger than 450 Sq. Ft. / 10 Ft. ceiling and opened to 3 other rooms with only 2 small separate backwalls totaling 44" wide.
I think we all can agree on that vibration is an enemy of quality sound reproduction.
In my case to get any decent bass required turning the woofer volume up to clipping levels (red Lt. blinking). Any amount of clipping causes the baffle to vibrate a lot more than the midrange is doing. Put your hand on the bottom of the baffle or mounting bracket. You'll be amazed at what you feel, I certainly was. Even turning the dial down to just below clipping, the bass woofer's vibration is still more than what the mid exhibits.
From looking at GR Research and Linkwitz speaker (which I was considering as replacements) design concept, I decided to add a pair of subwoofers to the mix. I have a common single 15 amp circuit feeding my entire playback system. I was afraid adding the subs would overload the circuit with the X5's power requirements. But, everything worked with no issues.
After tuning the subs and the X5's setting down to 1 notch above the 1/2 mark, I'm now a happy camper.
I'm hearing not only greater bass but a more fuller, detailed, musical presentation from top to bottom. The baffle's overall vibration is now, I believe, the lowest it can possibly get.
P.S. a great album to listen to for bass analysis is "Ten New Songs" by Leonard Cohen