Well, at that tension, one bad framehit or mishit can kill your racquet, so you'd better have great technique to use it. As well, you need a lot of power to flex the strings, but the amount of power you can get from higher tensions is incredible. However, if you don't have the technique and power, your power will suffer, and so will your aim, and your arm (those stiff stringbeds don't absorb much shock, so you'll have vibrations dancing up your arm). However, if you can handle it, you'll have great power, and control. But if you can't, don't try it.