I tried to use /UNILOG:logfile with robocopy and the output file is corrupt.
It has the UNICODE BOM (FFFE), but the characters that follow are ANSI, except for the line of text following "Options :", which does consist of actual UNICODE characters. However, immediately following that, it reverts back to ANSI, and if any of the files/paths in the listing really had a wide character, it is obliterated (appears as a single '?', so not even UTF-8).
I don't suppose there's any hope to see this fixed, since the story on Windows 8 robocopy is that it has even more bugs?