We haven't downed Omnitron yet (only had first few attempts on it on Monday) however I think it would be safe in saying that your Shaman and priest are under performing
http://www.worldoflogs.com/reports/r...ses&boss=42166
That's the WoL's for our attempts and myself was pulling around 8.5k hps and in the 3 mins of the fight (Omnitron at around 50% hp) I was down to around 60% mana. If you use regen puddles correctly there should be no way you are running anywhere near oom during the fight.
Yes paladins are performing exceptionally well at the moment but other healers aren't that far behind at all.
I should also note that yes I am also saying that the resto druid we had on that run was also under-performing on our attempts!