-1 from me.

- I hate to see Unicode exceptions here. It would be an another source of mysterious Unicode exception. Programmers and users would be confused by error message. If you make such characters error, Python should raise an OSError or such.

- File names with '?' are fine to display informations to users. Not all file names are nessesary to be used to open files.

- I don't think filenames cannot be decoded in ANSI code page are rare enough to be ignored. I use Japanese edition of windows, but I sometime receive files with Chinese or German names. 

Or, in some case, I have to change codepage with 'chcp 437' command to run console application made for American environment. I seldom run such application in these days, though.