You'll have more flexibility if you create your own setup, honesty. If you buy an Ebi/Flora, you'll have to sell and replace the internal filter and rip out the styro background. Really enjoyed my Ebi but added lighting, my own filtration, etc.
You can't cap Eco-Complete with sand - it will eventually settle beneath the EC. Go with one or the other. They're both inert and contain no plant nutrition unless you add it to the tank yourself.