There is a lot of similarity between the Econowave Deluxe and the Pi 4's Both are two ways with the upper section driven by the same compression driver but on different wave guides. The Pi's use a 15 inch JBL woofer the same as you would find doing commercial duty in their theater speakers While Zilch has reasons against the 15s he designs with 12s and uses a more economical choice in the econo deluxe. However if you want to save money the Pi's can also be built with an Eminence 15 and that saves $225 per speaker.
Some things to consider if building the Econwaves. As designed the ports are firing out the back and you will need to take the space requirement for the ports into account in your screen wall design. Second you may want to install the variable pots off speaker for ease of adjustment.
I've been tempted at trying a variation of the econowaves and the deluxe is highly rated. Wayne Parnham has been building, testing, demoing, and tweaking his design a bit longer and I have a little more confidence in his final design. You might want to compare the published measured results of Waynes versus Zilch's. If you can make any sense let me know.
Just so you know, Waynes plans are available for free just for the asking on his forum