My tapped horn subs, two of them, are big at 20 cf. per cab (and each weighing around or +200lbs incl. the driver, built in BB 13-ply), and handling such behemoths certainly isn't easy.
Once positioned is their respective corners (a placement chosen to flank the mains symmetrically and to take advantage from boundary gain) integration with the mains and overall acoustics from hereon has been a work in progress, mostly with regard to finding the proper delay setting as this has been done by ear (sorry, @mijostyn).
Tapped horns as well as the more classical front loaded horns can be tricky to hone in on wrt. delay (unless done with microphone + software), because there's not really a wave front outset to visually outline as a starting point, if you would, the way you can with a direct radiator. Some delay compensation with horn-based subs is a necessity, and knowing the horn path length helps, but with a tapped horn the front wave isn't initiated at the front nor back wave of the driver (positioned at the tap/mouth of the horn), but somewhere between the front side of the driver and the mouth.
Different delay settings have been been tried out via different presets, with a very good balance and mid bass energy now found. I have had my speaker setup (though with other, passively configured mains) measured out in both the time and amplitude domain and corrections done via software, but with my current actively configured setup I've only applied PEQ corrections (aided with measurements; completed by ear) on the top horn section via my Xilica DSP. A more complete software correction in both the amplitude and time domain may be implemented down the road.
To conclude: integrating my subs hasn't been downright easy so far, but having high-passed the mains beyond 80Hz, actively as well with subs sporting low group delay, decent phase behavior and no overhang, while having a professional, elaborate digital cross-over tool like the Xilica makes it a fairly straight forward process and a great way to harness the potential even further. Had I used digital correction tools to begin with the process would've been easier for sure.
As is the results are great; of-a-whole coherent sound, and totally effortless.