Typically, the flow in "rapids" isn't linear (that is, it flows a bit this way and that way, swirling, and going turbulent around the rocks and stuff), so using some "low pressure pumps" like the Hydor Koralia [1] to make the water move a lot in the tank will be perfectly acceppable way to keep these guys happy.
Large rocks, stacked so that you get crevices and gaps between them, and some proper "caves" (for example ceramic tubes or "hollowed out rocks") would be my setup if I had fish like these in a tank.
I'm sure there are several dozen other solutions that will "work" by some definition of "work" - to a large degree, it depends on what you like the look of.
[1] I have four Hydor Koralias of different sizes in my tanks, and I like them. But there are similar types of pumps from a lot of other companies that I'm sure are just as good, including some that are really low cost if you buy from places like Ebay.
In essence then a marine style powerhead ie the Koralia or something of that sort would be better than a manifold due to not being so linear?
If I were to get two say and place them on the right hand glass in the bottom third to half, what sort of change in flow should I expect for the top half of the tank if any? If there's not much change it would open up my stocking considerably from nothing (can't find any flow loving top ish dwellers) to all sorts of things probably not angels and discus but some activity at least.
I'm starting to think that perhaps a true biotope isn't going to work right now however a relaxed one would.
