I 5box and 10box on the same computer, previously it was a chore 10boxing and I could only ten box after zoning into a raid or starting at the stone and having the other 5 man group take a summons until I got an upgrade. Mixing two computers addressed the 10box issue easily, but the upgrade made it trivial to do on one computer.

I use camtasia and it works fine and I didn't even notice it (except when working with the application itself) even when 10boxing. Though I was only grabbing one slave's view 10boxing.

I have a separate server that I send prefmon, combatlog, chatlog, and multiplexer logging to.

I have recently gone to a three monitor setup. The traditional master + slaves, with half of a monitor is dedicated to spying on the performance & logging alerts (splunk!), vent, web use wowhead. The other half is a chunk of viewport from the master's session (all the unappealing combat, quest, chat, graph crap).