I think if Lucas really had all of the VFX elements, he should have actually gone through and recomposited EVERYTHING. There are way too many transparent mattes that could be elminated 100% if he actually had them. I'm sure he still has the CG files, but this whole thing comes from a post on a thread.
I don't think Lucas has the original VFX. It may not be true, but that's what I think.