I just tested the new "Mirror bleed when no bleed" feature in Optimise node which was added in 6.1, and turns out it is worse than the preflight profile made in Acrobat to do the same thing which I was already using via Preflight node.
The differences are:
Optimize node changes colors of the added bleed. If the document had Pantone colors, the resulting bleed is converted to CMYK. The preflight profile doesn't do that, and keeps the same colors on mirrored bleed as in the source.
Optimize node mirrored bleed is misaligned. It doesn't correspond to the document exactly. Mirrored bleed from the preflight profile on the other hand is aligned perfectly.
I see the problem. I have written a BUG against it. I do not have an outlook for a fix. If you raise the problem through Xerox support, it may result in the problem having a higher priority for a fix. Thanks.