I am a big fan of going fully active and have also used top notch components going with passives with great success but love the ability to fine tune with actives and overall results the best. I once owned a $7k, 25 years ago so would be much more now, pair of two way car speakers that were simply incredible as they should be. The passive crossovers looked like super high end small amps in a machined enclosure with foil caps, custom caps, very thick solid copper circuit board...yet I ended up testing then going right back to active. Of course part of that was the need for very precise tuning in the particular vehicle I had them in.
I also understand your need to do what you are doing and the fun factor of doing so with the bass department, great plan, sure it will do what you need and those look like a very good deal for the price on the (sub)woofers:)
Great drivers in the monitors as well!
Rick