I was taught the same thing (Australian secondary school, middle 1990s), but I only ever applied it to essay writing. It was just too much fun to take a quote that wasn't quite right and then make it right by employing a cunningly-placed ellipsis. I'd never use an ellipsis-as-pause in an essay, though. I'd also use different spacing: an ellipsis in an essay for me is always surrounded by spaces (and yes, if I'm cutting out the end of a sentence, then it'll be " ... ."); an ellipsis-as-pause anywhere else usually follows straight on after the word without a space.

Unfortunately, I was never really taught much about dashes.