Sandsifters and shellies are a no-go IMO, even with a large footprint. While not the most aggressive cichlid they definitely will want to rule the open areas which may create problems. I recommend them as species-only-tank fish.
I would choose a rock-dwelling species. Leleupi, julies, calvus, comps, etc. all fit the bill and would work perfectly in your tank.
I would also add to the cyp number as they really feel best in groups larger than 10.
THIS IS GOING TO BE AN AWESOME TANK I AM SO JEALOUS!!!!
Crap! That was the one wrinkle I was most concerned about because I can't find anyone that has direct experience. Without the Xenos, what do you think?
