@mijostyn --
Looks to be excellent craftsmanship.
Size is always an issue for aesthetic reasons.
It is, with all that typically entails. However, large size subs (or speakers in general) is not an insurmountable challenge to the minority who wills it, just like you willed it through with great effort via another path from a smaller size factor (in multiples) to keep even minute enclosure resonances at bay, not to mention the magnitude of the added weight of such sturdy built cabs with two woofers per unit.
The best solution is to cross out at 100 Hz, but you have to use a very steep curve or you wind up with subwoofer in your midrange which is poison. I use a 10th order filter, 48 dB/oct. The test is listening for voice in the subwoofer system, there should not be any or you smear the image. With shallow filters, even 18 dB/oct, you have to cross out below 60 Hz to keep the sub out of the midrange.
I find using 8th order slopes (i.e.: 48dB/octave) to produce a less desirable sonic outcome than 6th order L-R dittos (36dB/octave), but I also prefer using the same slopes throughout the entire frequency range actively, and I cross a bit lower to my subs - just below 85Hz. At the end of the day the ears are the final judges here, and context (incl. personal taste) is a factor as well.
Another advantage of having your subwoofer system active from below 100 Hz is increasing the gain on this segment between 10 and 100 Hz allows you to get the feel of a live performance without having to resort to ear damaging volume levels.
Also: the cleaner the bass the more gain can typically be applied without tipping the balance, and this way one can more readily appreciate the physicality of reproduction that's afforded here. Having the reminder of the frequency range configured actively gives you even further options to work with.
