Looking at half a screen at once is rather claustrophobic, especially when you need to see fine details and view the product as a customer would. Also sometimes I work as a build/deployment engineer. Yesterday for instance, I had to monitor 3 different windows at once and work with a very large list of files in 4 different directories simultaneously. There's really no avoiding it.
But anyway, I found a very small monitor I'm going to put off to the side just for tasklists or comms and try that for a while. I'm basically just trying to avoid alt tabbing because it's very disruptive. Refining my statement from earlier, virtual desktops are ok, but only for organizing COMPLETELY separate tasks.