You can do almost everything but controlling other units with a xbox 360 controller. You just need to take the time to map it to your own preferences.
I have 2 profiles, 1 for FPS and 1 for vehicle movement. This is 90% of what you can do in arma. The game allows you to set these controls individual for movement, driving, flying and other stuff so lot's of ways to get it work how you want to.
One thing that isn't that easy to do, or I haven't found out yet is to control the Gear dialog. Don't think voice recognition sofware can do that either.
Voice controls do allow you to control units and other advanced stuff, so combination of controller and voice controls will allow for like 99% of game controls.
Maybe BIS knows how to add the gears menu controls for other input than mouse.