On manicbotanix are several articles on Coco explaining the problem with different studies.From what im reading it can be done both ways? Can you elaborate on some of the specifics of the study and the reasoning?
Unfortunately, the page is currently down, so I can not look up the sources.
There was a study comparing coco and peat. It showed that Ca and Mg were present in the drain in lower amounts and K, S and Na in higher amounts than in the peat drain.
It can also be explained logically, since coco is still slowly weathering further and ions that were previously firmly bound are released.