I, too, would like to see someone come up with a realistic waterfall. I took a tour through the forums and have seen some very noble attempts---but so far nothing that's been genuinely realistic (all of which is not to say I haven't overlooked the perfect example!). I think it would help a lot to look closely at how real waterfalls work. Landscapes have a kind of anatomy: they look the way they do for a reason. Just as one shouldn't make up a figure from scratch without having a good knowledge of human anatomy and some background in drawing from life (and Poser is no substitute for this: it's one of the reasons such figures generally look awful), one should also understand how and why landscapes and landscape features work and look the way they do. TG2 is an astonishingly powerful tool (and goodness knows how much I appreciate that!), but I think successful use of it depends a great deal on making it do what you want it to, even if you have to do that at gunpoint. Sometimes, as I've discovered, it's simpler, easier and more effective to create an object or effect in post render. But I always try to give TG a fair shot at it first. I'm confident that someone is going to not only find a way to create a really good waterfall, but also by using a technique that's relatively simple, direct and broadly applicable.
For bla bla I would suggest finding photos of some waterfalls that resemble as much as possible the ones he wants and have them at his side as he tries to recreate them in his landscape. I think having some real-life models would stand him in very good stead.