I like good capabilities but even with those in the 30hz range I'll still use subs in any case, just better in the lower realm but I want the speakers to have significant drivers for larger rooms. Smaller room like my very small bedroom a 5.1 setup using 5.25" drivers and f3s in the high 40s/low 50s and two subs works great.
I also often se high end system with big speakers that should go pleanty loud and deep beeing used with subs, i personally won't go crazy, i just want a little higher sensitivity and more bass, i also for some genres think it won't do anything adding a subwoofer, since the kick, drums are above the freqency played buy a subwoofer
In turns of more bass,spl with the B&W 606 S3 it start's to have more bass,punchier bass than B&W 705, Dali oberon 3, Dali opticon 2, Dali rubicon 2 and my emit m10's, im just not shure it has higher sensitivity (only on paper) and it might be to much highs at high levels (listening fatigue), if the 606's has 3 db more power than i would have to have double the power for my dynaudio's to play as loud as the 606's, and thay would be enough.
The max spl i have is okay, i just don't wanna use all of the power my amp has to play loud + a little more tight bass
Spl goal could be mid 90's avarage 4-5 meter from the speakers or peaking above 100 db at 4-5 meters if i want a little more dynamic headroom.