I am hardly an expert but I do use both Elements and CS5. First off, Elements is very capable for a lot of things and is great value for money, because the CS versions are expensive. For processing well exposed digital images CS is generally overkill. But when I am dealing with old faded Anscochromes or (especially) Ektachromes gone red, the color correction tools in CS seem to significantly better. Maybe there are better tools "hidden" in Elements, but at this point I am happy to have CS.
Some before and after examples of my stuff can be found
HERE.
JBWX