I would suggest that if anyone is still doing the 'roll-your-own' approach with ShiftWindow, FancyZones or other window managers, and X-Mouse or Microsoft accessibility (focus-follows-mouse) options, WoW Open Box is a much better solution - it easily integrates the functionality of all those other tools. [WoW] Wow Open Box is released - fully functional open source, free, verifiably compliant multiboxing software (dual-boxing.com)

I'm sure there's some argument that people will make between JMB and WoW Open Box, and there are some minor differences. But in my opinion they are very feature-comparable. If you're going with non-broadcast software multiboxing, I think those 2 are the only viable options right now.

(If you're going full hardware - that's a whole other discussion).