IME, the highs from a distortion pedal or distorting amp sound, for lack of a better word, ugly, through a tweeter. A tweeterless guitar or bass speaker rolls the ugly off, leaving only the cool.
As far as risking the tweeter, it depends on the amount of power reaching the tweeter,
AFAIK. Distortion per se won't kill tweeters (I've cranked guitar amps throuth m JBL PA speakers before, and the world failed to end). But by definition as you make the signal more like a square wave, you increase the high harmonics, thus increasing the demand on the tweeter. Thus it's at least theoretically possible to kill a tweeter with a distorted sound, when a clean sound at the same SPL would not kill the tweeter . . .
