On user talk pages, if you want to move or change your own comment, it's better to strike it out. It avoids potential misunderstanding. Example,
Example thread
editUser "Example 2" wants to change their comment.
Moving - bad
editThe problem is, it appears that the 3rd user thinks sausages are cool. That is incorrect. User 3 hates sausages.
Strike-out is much better
editInstead of moving it, strike it, and add a note. ie :<s>I hate sausages. [[User:Example 2|Example 2]] ([[User talk:Example 2|talk]]), 16 December 2011 (UTC) </s> <small> Struck my earlier comment {{subst:user|example 2}} ~~~~~ </small>
This is clear. It's much better.