The only issue I have with FSS is that its terribly light. It's just heavier than water, its so light that if you have a slight current from a filter blowing on it, it will go everywhere. Or even just putting something into the water to trim plants can push the FSS everywhere.
I wish I would have known this before I did the scape on my shrimp tank because I would have made walls to help prevent it, this is my experience with it.
Otherwise, I did recommend it and to do as xmas suggested, full tear down.