CompareGeometry API

Hi,
I'm trying to use the CompareGeometry API, but it doesn't seem to be working. Even when using the gtResultShowUI option I don't see any differences on screen.
More to the point, I'm interested in the SaveCompareVolumeResults, which is marked as obsolete. I tried it anyways and it gives an error. This is strange, since it's possible to do this through the UI.
Has this functionality been moved elsewhere?

Thanks!