Welcome HAL! There are lots of Daves in the group, I hope you can get along. (showing my age here!)

I'm also a big planar fan. I've lusted after Martin Logan Monoliths for decades and I've owned Magnepans since 1979, when Gatt, may he rest in peace, introduced me to them.
I'm starting a new build you may be able to shed light and advice on. Look for it in "Projects".
Maggie ribbon, line array of Neo8 (both open baffle) and four Dayton RS180-4 enclosed in a linear array, same 24" wide panel, or at least that's the plan now. Wood is waiting to be cut. Have everything but the 8 RS180-4s.
Look forward to hearing your rig and advice!
Stuart