What I'm seeing on my monitor doesn't work together (marble looks dull and dirty -- more beige while the granite is glossy and grey), but to answer the question, if you put marble on the splash, it will etch. The character and chemical makeup of the stone won't change because you install it on a vertical surface instead of a horizontal one. In fact, your undercounter and hood lighting might make the etching more obvious. On the other hand, splatters on a splash tend to be fewer and smaller than spills on a counter. You have to figure out what bothers you. If you have a low tolerance, look at ceramic or glass. If you think you will be fine with it, look for a better lot of the marble.

I don't have CE, but our granite is also a dark stone(Labrador Golden Flake), so you might be able to get an idea from a pic of my kitchen. Our backsplash is a mosaic from Artistic Tiles--a mix of glossy and matte (frosted) glass strips in varying lengths and widths. The tile itself is clear, but is "painted" white on the backs. Because it is not Starfire/Starphire (aka low-iron) glass, it reads slightly blue-green in different lighting, at different times of day. In thses pics it just happens to look pretty white. Here are some pics for you:

Our glass tile (mosaic) backsplash is a mix of glossy and frosted/matte glass tile strips, which is probably more "forgiving" than larger, all glossy tiles would be. Unless there's an obvious splash or splatter (eg., tomato sauce, beet juice...), I have to remind myself to wipe down the backsplash occasionally, as it rarely if ever looks dirty. :)

A drawing of the hood elevation would help along with your inspiration photos. Without seeing anything I will say that accents behind ranges rarely work- they just look busy. Of course there are some very successful ones but largely we stopped doing them a decade ago. Post the cabinet drawings with dimensions so we can help.