While I'm not fond of any AA's, the jetpack in The Arena has to go. It is heavily exploited as a way to get out of a situation you were outplayed in and ruins many competitive aspects of Reach (if there are any at all). It's also commonly used to exploit map dynamics, ruining the purpose of map control. Now teams don't have to go through the regular routes to obtain map control. They can just fly wherever they like and often have a height advantage against players without it. The only real counter is using Jetpack yourself as seen nearly all of the single digit Onyx games I've played.
