I've done 100% water changes in the past on smaller tanks. Well, down to about 1" of water anyhow. Didn't have fish though to worry about in that particular tank. But, it sure cleared up a high nitrate buildup lickedy-split! Corals were fine through the ordeal. They slime up a bit, but, the slime sluffs off eventually.
In my experience, in general, larger (eg. 40-60%) water change volumes are not that bad as all that. Yeah, water is cloudy initially, but after a day and it's cleared up, everything just tends to look awesome for it. New water I guess just tastes better for everyone who has to live in it.
