To archive or to noarchive?

What do people think about using

<META NAME="ROBOTS" CONTENT="NOARCHIVE">

on their forum pages?

I'm thinking about disabling Google's caching of our pages. Our Google cached formatting looks terrible, new posts and threads are missing, and the cached pages pull up old ads.

Am I missing any positives?

This will also block archive.org from saving your site.

IMO, the amount of cached views isn't worth the end result. It's always fun to look abck at your site 5 years ago and see what it looked like back in web 1.0 days :P