You can add custom fonts, textures, sound files, etc. all with only using ElvUI. The media file that ElvUI uses is the same as SharedMedia. The borders are also a clear indicator of Elv unfortunately. Alternatively you can turn it to a pixel and disable the ElvUI border from the LUA and can recreate everything from the more popular addons here with just a couple of extra addons (notably Raven, Weak Auras, Raven, Gnosis, and a minimap of your choice).
I've actually taken this "challenge" on for myself and fully recreated Kait's UI. Once again the argument comes up that just because the user can't use his tools adequately doesn't mean that the tool itself is inadequate. (lol penis joke, etc.)