We did this on the 7100 we used to have albeit the coverage of the foil stamping was light coverage, and it seemed to work well. However one thing to not is if the foil image was not fully applied/transfers (little bits of edge trim around art/object that didn't release cleanly) it will track onto your fusing belt and the web from what I could tell has a hard time cleaning this off. Printing over foil or into foil, which I was asked some time ago, I can say is a no go by any means. But that is obvious as to why.