The sidewalls on the ATs are pretty strong. But if your planning on wailing on the sidewalls, I imagine the type of surface you will be on to do that will not be very freindly with the ATs. The BFG AT is a great tire and will hold up fine for very light trail duty. But its not meant for the mud, its not meant for the rocks. You just won't have the traction you will get out of the MT. Not saying you'll have no traction, but with a skinny foot print on an AT, it will be "interesting".
I have wheeled with both and though the AT will allow you to have some fun there is just no comparison off the road with the MT.