Physically Eco and Flourite should last just like Rex says. Nutritionally, both should be as long lasting as an aged gravel substrate. Eco starts out nutrient loaded, Flourite starts out with a high CEC or ability to adsorb nutrients from the water column and store them. Plants (and bacteria) can break the bond that Flourite and Eco has on a nutrient ion to use it. You have to supply nutrients in either case, but the substrates will be there for a long time.
Aquascape? I'm a crypt farmer.
It's a fine line between fishing and standing on the shore looking like an idiot.
That IS an aquascape, it's titled "The Vacant Lot".