All this talk about smoke ... yes, it's usually near-invisible. But here's HMS Inflexible (allegedly) at the Falklands, renowned for being one of the smokiest engagements of the War. Black smoke => bad spotting => awful hit rates.

That's very black indeed.
That said, in the balance between "no smoke" and "white smoke", I think I'd prefer some visual effect and go for white smoke for my Dreadnought - especially when the output is just water droplets which are neither going to stain the model nor destroy the environment.
Andy