Not to jump into a debate on Leppard on a ACDC thread, but Joe's voice was good enough to earn him 2 diamond albums. I don't know many other bands in the 80's who pulled that off. Actually, I don't know of any other bands who pulled that off.
As for his range, Rocket, Love Bites, Photograph, Rock Rock Till you Drop, Stagefright, Die Hard the Hunter, and others are pretty high up there. It takes a swift kick in the nuts to hit the chorus on Love Bites and Rocket. Slang showed off his lower register as well.
You forgot their best song. Let it Rock. Let it Roll. Let it Go.
Always liked Joe. I think he is unfairly lumped in with his imitators (acknowledging the fact that Joe himself took his cues from Robert Plant) in the hair bands of the 80s.
Hate to sound like a 'first/second album' pedant but I did like DL when Pete / Steve were the guitarists (esp High N Dry). Saw Pete on a Behind The Music and he's a tiny little guy. Also looks like he's been dragged behind a truck while sliding on his face.