Came here to post this and the most recent post covers all the bases.
In ARMA2, I was mediocre at best when it came to flying with the Keyboard and Mouse. I don't really fancy the flight stick option as it costs money I don't have and it requires me to drag out a peripheral whenever I want to jump into some ARMA. The controller support for ARMA2 was just so that I could customize my controller to effectively fly helicopters with ease. The biggest benefit was the use of the two sticks to fully incorporate an easy maneuvering style into my gameplay. Keyboard and Mouse doesn't allow for that (at least for me).