Jeff,
Are you running GFO to tackle an algae issue or for just general maintenance to keep phosphates down?
I have not had issues running the recommended amount that is usually listed on the product. Usually the only problems with GFO is that it will take too many phosphates from the water! Corals need a certain amount of nitrates and phosphates. I sucked so much out of my tank at one point my acropora began to lose a bit of color. Increased feedings fixed that pretty quickly, though.
I doubt that peeling skin and the shrunk of leather are directly related to the GFO. It is most likely something else. Leathers in my experience are very fickle and will close up for no reason. The peeling acro is a sure sign of a problem on the other hand.
Slow tissue necrosis is most often due to low alkalinity, less that 7.5 DKH, or a swing of a few points in a short amount of time. It can also be caused by stress from elevated nitrate and phosphate levels.
What is the current status of your tank as far as algae and nutrient issues?
I would hold off on the GFO and do water changes every other day of around 10-15%.