The hector_quadrotor stack offers you a simulated quadrotor that can be controlled through geometry_msgs/Twist commands. I'm not sure if the asctec pelican offers a similar interface (it sure would be good if you want to use the navigation stack). If you need to use other control commands you could either write a node on top of the currently available controller or have a look at the gazebo plugins and write your own controller plugin.
In the end, SLAM (see hector quadrotor indoor SLAM demo) and the use of the navigation stack are possible on the simulated quadrotor, it's just a matter of interfacing/glue code. The problems (no odometry available, 6DOF motion etc.) are largely the same, regardless if it's a simulated or real quadrotor.