If we're talking about the plate style LSD from a 944 then that should reduce the likelihood of spider gears imploding obviously.... That's the primary benefit at least in my view. Have personally installed a number of these LSD's in 016 boxes and run pretty big hp/tq through them afterwards with no issues. But then again, I'm not a total monkey with the throttle and drop clutch starts.
The plate provides some much needed reinforcement to the rear of the cast iron housing, and that's helpful in all situations.