I have been using one of these E&L Manufactuerers flat top brass catchers for quite a few years. http://www.elmfg.com/store/univbc.html
In that time it has caught thousands of rounds from 3 different ARs without a single malfunction induced by a case bouncing back into the action. Any malfunctions were caused by incorrect user manipulation of the rifle. The trick to no malfunctions is to not tilt the rifle to the left far enough to pour the cases out with the catcher attached to the rifle.
This model catcher comes with a set of rods that attach to the picatinny rail and the catcher body attaches to the rods; easy on and easy off. You can buy the rods separately and use the same body for multiple rifles.
I have used the cheap Caldwell, but the brass melts to the netting with my sbr. This looks like a much better option.
I just throw a rag towel over my gun and let all the brass drop next to the rifle.