Separation and the River Forest Debate

The suggestion may be naive. Here 't goes. The debate is well known. Is proof of the existence of a being that cannot be material required before the separatio of being from matter can be achieved? Gilsonians say no; River Forest / Laval Thomism says yes. 

Remark: The Platonists seem to have a valid argument for The One from the many. (Though perhaps someone will dispute this. I find it compelling.) Yet, they reject the predicates "Being" and "Intelligence", etc., for The One. 

Thus, the question: Is it even sufficient to infer The One in order to determine the freedom of some perfection from limitation?