I have had a Leica 1200 and a Bushnell compact 800 and for ranges <300 yds. the cheaper Bushnell was fine. You may have some trouble ranging directly on a gh.....I have never tried. But while shooting prairie dogs.........which cannot be ranged well with either unit, we usually range something close that is reflective enough to give us a good reading .....ie, rock , mound, fence, change in topography or even a target stand that we move around for reference.
If you want to give yourself an idea of what you are up against...take a pair of decent 8x binos and hold them steady on a 12" target at 300yds. Some rangefinders don't have quite that much magnification but the problem is still going to be holding steady. Even when I tried a LRF for big game hunting I found right away that ranging something close in distance and larger in size was much easier than a direct range on the animal.