I've often wondered myself just how fatal a minor ick out break can be....I'm aware of the treatment options and twice I've had to deal with minor ick outbreaks in my reef.
First was when I added my coral beauty about 18 months ago and the second was after adding a hippo tang(which was quarentined for 8 weeks)...both developed a minor infestation shortly after being added to the reef....each was treated with garlic soaked food for a few weeks(once a day every other day). The coral beauty never has shown signs of ick since it was treated and the hippo has been in the reef for maybe 6-8 weeks now and still shows a bit of ick now and then( I still add garlic a few times each week).The hippo has dramatically improved since I first saw sighs of ick...and appears to be healthy.I might mention that for close to two years now I've added garlic to the reefs food once a week as a normal practice...but increase the suppliment of garlic immediately whenever I've seen sign of ick.
I agree that the first course of action should be to eliminate stress and poor water conditions...plus it appears that supplimenting garlic may help.
In both instances I've not gone to the extreme of removing the fish to quarentine tanks for chemical treatment or hypo-salinity.Although I know that both are suggested treatments....I've simply eliminated the potential for stress and supplimented garlic. This process has seemed to work for the minor cases I've personally dealt with...and I in no way want to suggest that chemical treatment in quarentine or hypo-salinity are not needed in some cases.
It just seems that in the cases I've had less radical alternatives have apparently worked and the fish appear healthy without progressively getting worse.
I would like to add that in the disease & treatment forum Beth can give additional detailed info on questions of this nature...but for me the less intrusive methods have worked to deal with minor ick outbreaks...and I still wonder just how fatal minor ick outbreaks are....