Ok, the other day we were running Kara - some of us were using KLH Threat Meter and some were using Omen.  It seems none of us could see everyone's threat...  I just read something on the [url=http://wow.curse.com/downloads/details/9101/?cpage=1#comments]Omen page[/url] which leads me to believe that [url=http://wow.curse.com/downloads/details/4204/]KLH[/url] and Omen are no longer compatible:
[quote:c9af48cdac]Omen is an interface for the Threat-2.0 library ... To get fully accurate data, your groupmates must have Threat-2.0 ... installed.  ... Please note that unlike Threat-1.0, Threat-2.0 DOES NOT have KLH Threat Meter interoperability.[/quote:c9af48cdac]
KLH has been around longer, has more users and kind of set the standard afaik.  The last &quot;official&quot; guild word was that we would use KLH.  However, Omen was compatible with KLH when it became available so it didn't really matter.  It apparently now matters.

Both addons are actively being updated, Omen was last updated on 3/29 and KLH on 3/28.  The Omen page does indicate that WoW patch 2.4 includes code that will make it possible for all addons to tell one mob from another even if they have the same name.  The Omen author has code included to show different aggro on different mobs, but it doesn't work well yet.  The KLH author is working on coding this into his addon as well, but has said he doesn't want to release the code until it's working properly.

I prefer KLH, but I'll run whichever the guild decides.  It's just that since the two are apparently no longer compatible I think we need to all be running the same addon when we run together.