Yeah, but the point would be that DPSer is so easy to play compared ot Tank/Healer that having to internally calculate your Threat from your damage done versus the tank (and you should know your tank) is the only thing putting some brainpower in to the fight.
Rolling your head over the keyboard with half the keys bound to Attack #1 and the other half to Attack #2 is hardly something of a big feat.
Pot. Kettle. Black. Which are you: Tank or Healer? It's easy to point the finger at the other side. Personally, I always blame wipes on the Healers. Then again, I guess it could be the Tanks. I'm DPS so I know it can't be us :)
Back to the real subject:
Someone else already posted this idea, but I think it deserves repeating.
Pick a relatively recent version of Omen, one posted 2-4 hours earlier that didn't have an immediate update, and post it or a link to it on your guilds website/forum and have everyone run that version. Not that version or newer or close to that version, but that version. Since we started doing this it's been a lot better for us. Yes, some people have to downgrade and some people have to upgrade and it has delayed the start of some of our raids. But, having everyone running the same version of Omen and Threat has pretty much eliminated our problems.