An armored Batman *has* to throw some Iron-Man related joke.
"Your armor is all black?"
"If I wanted my enemies to spot me from afar against the night sky, I'd paint it yellow and red. I'm not that silly".
I have no idea how they're going to manage a World's Finest movie. The Batman/Superman dynamic is kind of complicated and subtle, and I don't know that it can be explored in any meaningful way in a two-hour movie that, in order for it to be exciting at all, has to feature a villain that Batman and Superman can both fight together, which probably means Batman building some awesome suit of armor, and okay, I'm excited to see it, I admit.
My point, though, is that I basically expect non-stop action rather than the stuff that actually makes Batman and Superman interesting foils to one another.