Six windows on the same screen? That's way too crowded; I rarely have more than three. Virtual desktops are natural to use, don't enjoy working without them. I use i3wm and often move between windows using the mouse.
You can easily fit 6 windows of apps that aren't wasteful of screen space on one monitor, even without overlapping them. I find that quality Mac apps scale gracefully, whereas things like Gnome 3 apps have giant CSD chrome and don't scale particularly well. And if you do overlap windows, you can fit even more if you arrange them well so they're easy to access quickly.
