It's not necasserily the fact that it's a "prop"... Sure, the 2fort sniper fences, badlands spire, sawmill waterfall and nucleus spinny thing that get so overused are props, but really it's just that they're so unique and thus recognisable. Like the hydro bowl. That's not a prop... but it would be equally cheap pasting that it into your map. IE It'll still be the hydro bowl, just now it's in your map.
Making it out of displacements only inadvertantly works by making it not look like the badlands prop (Which should look cool if done right and designed well). Though It will be really time consuming, and probably a lot more effort than you'd want to put in for an alpha (make it func_detail brushes first, then change it in beta), but atleast you can control the height.