I know it's just anecdata, but I had plants that were getting steadily smaller/dying in one tank with a gravel substrate. Once I shifted them to a tank with eco-complete, they revived quickly and are thriving.
My tanks are still quite young, so I'll need to monitor developments carefully, of course. Other people who have had tanks for years have told me that they use eco-complete and recommend it. They do supplement for their own water deficiencies, of course, as I mentioned that I do for the potassium.