GJ,
I really NEVER did the "loud as we could" thing. I always had individual stage monitors, and never had the mains in a damaging position. The only real thing the dancers need is BASS. That what drives the feeling in your gut - you can "feel" it. Make the bass and drums dominant, make the vocal sing out clear ABOVE the rest, and they'll dance. The've been doing it with me since 1969, and I have no "ringing" or deadening of high end.
Speaking of th4e Beatles - look at any pictures of their early concerts - there are NO pa speakers or monitors in sight - just those low powered Vox amps at the back of the stage. I don't know HOW they did it, with all the screaming in the house.