What is survival rate for moving established tank?

[Hightower]

I am looking to buy a reef setup. Be it new or used.

If I go used, and there is an established tank in place, and it is to be moved, what are the chances that everything will survive, and how much stress will be on the tank inhabitants.

Furthermore, how can you move tank inhabitants, rock sand water, etc with minimal downtime and least amount of stress for them?

Any experiences?

Thanks