Whether to use real rock or faux rock is a good question, some of the things you need to consider before deciding… Do you have the great rock carvers available to you? Artificial rock carving is a real art, not anyone can do this including you the owner. You will need to seek our these craftsman, interview them, see their work personally not photos, they could be showing you someones else’s work, speak to the owners of the rock work and ask how it is holding up, are there problems with leaking, settling or cracking, look at the paint job, this is also an art, an awesome rock carver is not always a great painter, an unskilled painter can make the most amazing rock carve job look like elephant dung, do your home work.
Now the next question to ask your self…Should I use real rock, another good question, do you have rock, boulders available in your area? do you have crane or fork extension lift access to the waterfall location? You will have to seek out the right craftsman for the job, someone who can stack rock to look natural not just a pile of rocks, someone who knows how to make the water flow naturally. Try to stay with the hard rock choices like granite, sanstone and other soft rock materials will come apart rather quickly and the hard water will absorb into the rock leaving behind an unsightly look.
Both rock features can have a dramatic effect on your project, do your homework and make the best choice for your pool and it will look awesome!