Hi all,
I think most Apistogramma species would be all right with the flow, as suggested in a large tank there will always be places where the flow is less strong. Again as long as there are darker areas down towards the bottom and lots of cover the light won't bother them. Apistogramma trifasciata or A. borellii are good ones if you can find them, they don't need too low a pH and they stay small. I'd also put in a good word for Apistogramma "Steel-blue" in a larger tank, they are easy to keep, but quite aggressive. If you prefer a red fish, either A. agassizii or A. cacatuoides are easy to obtain and keep. A. cacatuoides is a bit bigger than 2", but if you don't mind slightly bigger either A. hongsloi or A. macmasteri are also possibilities.
If you can keep the water soft and the pH below 7, all of A. baenschii, nijsenii or panduro are stunning fish.
I like Checkerboards (Dicrossus spp.) as well, but they are much more difficult to keep, they really need very clean, soft, acid water and lots of live food and I would keep away from them unless you fancy a challenge. Another possibility would be a Dwarf Pike Cichlid, Crenicichla compressiceps, again more of a challenge as they are very territorial and aggressive. They really benefit from a strong flow, as they are rheophilic in the wild.
cheers Darrel