I'm using v2.39j. My tagging options are to write ID3V2.3 ISO-8859-1 (and no ID3V1 tags).
I am using the ORIGYEAR tag to store the year a disc or album was released and the YEAR tag for the year the song was originally recorded. I know this isn't perfect, but it's the most compatible with the other players that I use; both software and hardware.
I have noticed something strange: I usually go through all of my tagging with Mp3tag, and then calculate replay gain in Winamp. When Winamp writes the replay gain tags, it wipes out the ORIGYEAR value. I tried the same thing with Foobar, setting its tagging option to the "non-specification compliant" mode to make it write v2.3 tags (instead if its default, which is 2.4). It does the same thing.
Don't know if this a bug or not...