It may depend on the density of the Eco-Complete vs. Sand. I was under the impression that the finer particles will remain on the top and coarser on the bottom. I'm in the process of planning my Discus tank, which will have some plants. I planned on trying to keep the sparse planted areas separate from open water (120 Gal amazon basin). I was going to layer the planted areas with Volcanit-Euro M & F in the planted areas. The unplanted areas would be a mix of Carib-Sea's Peace River and Crystal River substrates. The Vulcanit will be topped with the Crystal River which is the consistency of sugar. I'm hoping it works.
Bump: PS: I'm planning Bristlenose Pleco's and Farlowella for my scavengers.