I find that smaller cichlids do well with larger ones in my tanks, as long as they are not small enough to be considered food. The larger fish seem to ignore them, I have more problems introducing a larger fish than smaller. The only problem is the smaller fish seem to grow slower when mixed with larger fish and grammodes grow extremly slow so that might be a problem for you.
+1 sort of... I have had good luck mixing larger fish with smaller fish as long as there are plenty of hiding places/obstacles, and the fish are not so small that they will be eatin. I currently have my centrarchus pair(3.5-4") with my pair of hogs(8-10"). The hogs for the most part ignore the little centrarchus. They are more concerned with eachother. They don't really see the cents as a threat. Not too say they will not be chased but not excessively. As far as slower growth. Not in my experience. My little guys are usually capable of getting food right with the big guys.