Alright I tested some more and you are correct, it messes up regardless of which method is used to reply. This is clearly a postlist indentation bug in 6.5 then.
Hmm, there is no rational explanation for why it should be behaving like that. I know it doesn't do that in 6.3 (not sure about 6.4).
If you want to PM me your FTP login I can try fixing it (after backing up the original of course), it's up to you.
