How do you know when it's the user who refreshed -vs- an ajax refreshing?
Ask your members ?
Also what if they see something and want to compare it with a view from a different browser and automatic refreshing clears it away? They no longer have the option of doing a screenshot, etc.
Probably very rare, but I see kind of what you mean, if someone sees a topic they want to click on the index then go away to the door or something they then come back and it could be gone from the topic view and they would have to go into the forum and look for it.