Mixing Substrates - anybody done it?

So I have a bag worth of Flourite in a 10 gallon tank that I am planning to move to my new 38 gallon tank. My plant growth has been lackluster, so I already bought 2 bags of Eco-Complete for the 38 without really considering the implications of mixing the two substrates together. Chemically I don't see a problem with mixing them together, in fact it seems like a good way to get the best of both substrates. However, I have since realized that it will look funny if I blend them evenly. My current plan is to put the flourite on the bottom and have the Eco-Complete on top to provide the nice clean black. The hang up with that is just with cleaning the substrate during water changes. I'm worried I'll get patches of the flourite that come up when I use my syphon to clean the gravel or that my firemouth, who likes to dig pits, wil expose and start moving the flourite. If I get enough lighting and CO2 I should be able to get by without cleaning the gravel (build up some mulm right?) but until I can afford a second 96W fixture I would like to be able to clean the bottom, and I don't ever see the firemouth not digging. Does anybody have any feedback, advice, thoughts, etc. on the topic? (Sorry this turned out to be so long)

I saw somebody who had used acrylic to define a path in their substrate, but I don't think I want to deal with bending acrylic, and that seems cool when seperating sand from a plant substrate where you plan to put plants in some areas, but with two plant substrates I would just be putting plants everywhere anyways. Should I go for an even mix to start with, or try to keep it layered and not clean deeply?