the difference between the skimmers is that the reef ready version has an extra chamber for bubble reduction instead of a large open chamber for biological filtration media (whatever they call that blue stuff). right?
Depending on your usage of live rock in the tank, and how well the CPR actually skims, it shouldn't make a difference whether or not you have bio media in there.... I know that nitrates don't play that much of a role in a FOWLR, but i'd still say that bio media would be a nitrate factory...