As a BIG Supes fan I'm going to have to stick to my assesment that Dean would be able to pull off being Superman in the Worlds Finest movie. While I enjoyed Lois and Clark it was never meant to be the adventure fest that we expect Superman to be. However we did learn that Dean could easily play a convincing Clark Kent so that's half the battle. On the Superman side I think a better suit, a better director and better effects could really give Dean the chance to shine as the Man of Steel.
Much like Tobey McGuire in Spider-Man I honestly think a big budget Superman role could seriously catapult Dean's career as he would give a convincing appearance of the Man of Tommorrow.
Nightwing - Ripleys came out a few years after Lois and Clark had ended.
"Never give in--never, never, never, never, in nothing great or small, large or petty, never give in except to convictions of honour and good sense. Never yield to force; never yield to the apparently overwhelming might of the enemy."
- Prime Minister Winston Churchill
"Si vis pacem, para bellum."