There is nothing wrong with Rush in Rio, it was a loud live concert not a studio recording. Same way with Iron Maiden in Rio. Very big crowds of energized people who know and sing all the songs during the concerts. AC/DC Live at Donington is a somewhat similar large crowd concert DVD experience.
U2 at Slane Castle is very good, as well as, Peter Gabriel Growing Up Live, Roger Waters, Dave Gilmour, Led Zeppelin, Tom Petty at the Olympic, SRV at el Mocambo. All of these have been regulars in the CX1 player. The visual effect of Peter Gabriel's DVD is very powerful projected on a large screen surface (besides having great sound).