I disagree that is a waste of energy. They are artists and work on their craft like any other performer. In fact "screaming like idiots" just shows your ignorance. I work with all types of performers from jazz to opera to metal and they all take practice, stamina, and are extremely difficult to do well.
Cupping does suck, but I can't control that.
And if this mic is that awesome, I believe that it should hold up to the fairly typical stage environments I see all the time. I have $12 mics that are wired, but don't clip or distort with screamers or loud singers, and with cupping.
I prefer wireless because it allows greater mobility for a performer. Also in rowdier environments it starts to become a safety issue. And I am willing to invest more if necessary if it will help with the clipping issues. But I want to be sure and I think the answer would be valuable to anyone else looking into this product either for their own bands or for sound companies like myself.