Here is a link to Dr.Rons thoughts on quarantine
here . I have followed this logic (though I do use dips on coral before introducing them to my tank.)
I found it interesting that he says that copper treatments will reduce the life expectancy of the fish treated with it.
Anyhow, I guess the decision is ultimately up to you, as the post above states it is easier to deal with the loss of $50 than $700. I only keep three fish with my coral and if/when I introduce another it will most likely go straight into the tank as I do not think that I could set up a quarantine tank with conditions as good as my established tank and think that the stress of poor water parameters (IMO a newly set up tank will not have the stability it would need and I can not justify keeping a tank as a quarantine/hospital when I only have 3 fish.)
Just thought I would offer another point of view.
-Danny