My decision to use copper to treat ich was primarily based on this website:
http://madhunag.tripod.com/diseases.html
"Coppersafe: Very safe when used in the recommended dosage. Kills Ich, Flukes, Anchor Worms and Velvet parasites. Works slowly, a drawback (takes 21 days in some cases), but it does kill them. If treated for less than 21 days, Ich will come back. (Also true for other anti-parasite meds, by the way.) Not toxic to any fish. Sometimes does impact delicate plants, but they recover quickly after the Coppersafe is removed. If I had an expensive prized plant, I might remove it to a 5-gallon aquarium for safekeeping while I treated with Coppersafe, but in actual practice I've not had problems with it. You could put the plant(s) in a 5-gallon tank, add YG, place near a strong light (a north window, perhaps), and the plants would think they've been to a health spa. Kills shrimp and some snails. Safe for cycle bacteria. Compatible with other Mardel medications such as Maracyn I and II.
Salt/Heat: 1 tablespoon salt per 5 gallons of water, 87*F temperature. Safe for 99% of fish, completely non-toxic to fishkeeper. Safe for cycle bacteria. Works slowly (21 days) to kill parasites, but well tolerated by most fish and shrimp. Not recommended for Tetras, Corys or smooth-skinned fish such as Kuhli Loaches and Clown Loaches. If the fish can tolerate heat/salt, it's the treatment of choice. Rough on plants, which usually show visible damage after 21 days, but which grow back after salt is removed and temps lowered. Treatment of choice for Guppys, Mollys, Platys, Swordtails. For live bearers salt can be added at 1 table spoon per 1 gallon of water. Mollys can take salt up to 1/2 cup per 5 gallons, which kills external parasites very quickly.
and my grandmothers recommendation, she used copper to treat her fish for over 25 years with no ill effects.
I have both Tetras and Corys, no live plants and no invertebrates so copper seemed like the best choice. Ultimately it worked like a charm and the fish are doing well.