With the beginning or MoP, we had our main tank and one of our excellent healing-only healers take a break from raiding. One isn't even level 90 yet. We have tried to replace them a few times but it's been difficult.
This week we brought into MV a new off-tank with 3-4 greens and trialed a few healers (one a dps who re-rolled a pally just to help out). It was pretty rough. It's unclear if we've turned a corner on the healing; Across the board we seem to have connection issues or lag issues or skill issues or a combination. The off-tank is learning quite quickly which is great.
It still took us 1.5 days to get to Elegon and then we wiped there a bit. We had been doing 4 orbs the first time around and 4 orbs the second time around. We had one of those crushing single-digit health percentage wipes during the healing-intensive part. So then we decided to try and get to 5 orbs the first time and 4 the second to buy a bit more killing power. That did the trick. We killed him a good 15 seconds quicker than the previous attempts had been tracking.
I still need to get our off-tank to count better before pulling bosses so I can pre-pot like I do with the other tanks, but a kill is a kill.
I'm concerned that we out-geared this boss from a DPS standpoint and still don't have the tank to take less damage and the healers to handle even a well-geared tank.