LOL
That is precisely what I have in my tank. My tank is heavily planted as well (my cichlids are plant friendly), so that means less cleaning of the substrate. But the parts I do clean, I basically have to wave my gravel vac/water changer over, kicking up the debris trapped underneath. Burying the vac in the mix as you would with gravel will just suck out all your sand. My fish love the mix, and have built spawning pits just fine in it, so it must not be too bad! I once tried mixing some lava rock colored eco-complete substrate with a tan sand, and it just made the sand look like it was dirty even though it wasn't. The black on black has a really nice look to it, and brings out the colors of everything else in the tank much more. White on white would look nice too, but I would imagine it would drown out colors, and show dirt more.
The most important thing to keep in mind if mixing like that, is to evenly mix the substrates together prior to putting them in the tank. Do not put gravel down, and then a layer of sand over it. Doing that creates the perfect conditions for food & waste to get trapped under the sand layer, which can decompose over time and create pockets of gas deadly to fish when they make their way through the sand. Even with a gravel/sand mix, you need to be sure and stir the substrate up every so often to break up any air pockets where the gas might form.