The recent nerf to Dragon Soul with the release of patch 4.3.2 means more players are now within striking distance of Morchok on heroic modes. He's a boss that serves as an execution check for your raiding group more than anything else. If your raid group mastered the art of healing through him on normal, then it should have no problem doing it again on heroic.
Just be prepared to do it twice.
The biggest hard mode change is that Morchok clones himself. His clone has the exact same abilities as Morchok prime, except the timing will be off. Your raid will be splitting in two and pulling the two bosses away from each other. You can envision the fight as two pseudo 10-man groups fighting (or two 5-mans, if you're in a 10-man raiding group).
Come into the raid with six to seven healers, if you're a 25-man raiding group. Actually, I'd consider bringing seven if it's the very first time. For 10-man, it is not uncommon for groups to bring in up to four healers for the first time. You'll need them, due to the amount of damage being dished out to the raid. Ideally, try to insist that when your raid leader splits the raid into two groups, the players will show up in your raid frames in different groups. Having all of the players in group 1 and 2 on one side with groups 3 and 4 on the other can be beneficial. The side that is tanking Morchok is the one that could benefit from the extra healer, as it seems more damage is done on that side.
I strongly recommend bringing in tanks with their four-piece bonuses, because they will be an incredible asset.