Personally, in Guatemala, I see most of lower quality Arabica beans are from mono-culture farms at lower altitude, with heavier production. No shade grown, just coffee plants, nothing else. Also, most of Robusta in Brazil & Vietnam apply mono-culture.
However, most of SHB (strictly hard beans) are from Poly-cultured farms, higher altitude and cooler climate. The beans must have some shades (banana plants for lower altitude, Avocado trees and lemon trees for higher altitude) in order to grow slower. (too much sun will make cherry ripe too fast which means loses flavors and characteristics)
for perma-culture, it is not practiced, nor even possible in Guatemala.
I am sure that most of people knows about this, but it is a "philosophy" of working together with nature, including other plants & animals in their all functions in nature. And now, when we talk about perma-culture, it even has expanded to include economic & social system, in this case, coffee system.
if you ask me, maybe this might be possible in "kona island" for Kona coffee that can demand 3 times of pricing than other 3rd world country coffees.