IRC definitely changes when there are logs. Sans logging, it's a lot like a face-to-face discussion; you try not to say anything *really* bad but you worry more about making the communication work.
Once a channel is logged, you have to think a *bit* more about everything you say. It's still pretty informal but you need to be more careful to avoid saying something that gets interpreted completely differently from what you intended and then hangs around on the logs incriminating you until the next disk crash.
Maybe we could compromise somehow; logging but on a server with a single old hard drive and no backups