I have never had "Miracle Grow Potting Soil" to kill a Plant??? I have grew some Monster Banana Pups in nothing but MGPS!! I really like it alot myself. I have used it for about 10 years and to my knowledge it has never killed a plant or harmed one.
One of the top Banana Plant sellers(Ted Taylor, of GreenEarth Inc.) on Ebay, actually recommends you to use "Miracle Grow Potting Soil" to pot the plants he sends you!! Just my 2 cents worth.