While it's a nice achievement, visually I find it nightmarish. I don't understand how anyone can focus on 2 panes + PIP in the corner. For me 2 panes is more than enough to occupy my attention. The "iOS Expose" sounds like it's a great way to emulate having multiple monitors on an iPad without having to clutter the screen with more than 2 apps at once (ok you can do 3, but really I find it more distracting than productive)
Even at work, although I have a 28" and 30" monitor side by side, I only keep at most 2 large windows as the focus on one screen, and never look at both screens at the same time....