I haven't owned a 911 enough to know the handling differences but everyone always says they are harder to drive and don't handle as well.
I recently read a MotorTrend article that sought to find the best handling car in America.
The GT3 was the winner with the Cayman S in second place.
MotorTrend - Best Handling Car in America
It sounds like the Box is easier to drive and less precarious but if you know what you are doing the 911 (at least in GT3 form) has better handling?