We had the entire raid download the latest Omen last night (4/1) before the raid.
From there we got many problems including the biggest one of Omen not showing raid members unless they "/console reloadui" after they zone back in to the raid zone after a wipe. For some reason zoning after a wipe as a ghost seems to cause Omen to stop working completely for that person and they have to '/console reloadui' in order for us to even see them anymore.
Other problems were one time Omen appeared to crash every person in the zone that was using an Nvidia card, that was a fun one.
EDIT: After reading the post above mine, maybe the non crashers were using earlier versions (some people don't understand "log out and update omen" before the raid starts, heh). All I know is like 18 of the 25 people crashed during trash wave 8 of 8 on the second boss in MH, not a good time to crash the raid. :p