Changing aiming accuracy alone based on bot classes will likely lead to some of them being consistently "weaker" than others.
IMO a proper approach would be to counterbalance this with another parameters (for example, the worse the aim, the faster the yaw speed, so it would mimic better a "twitching" player).
BTW, I am looking forward to play the final result, it's an awesome revamp project you guys are doing here.
