Breaking it down further, christ:
Goal #1 -- Keep chain alive. Gravity isn't going to lower the evasion of a mob that drastically that will make up for ANOTHER melee in the party. Gravity has a high recast time, if you're killing efficiently you're not gonna have it ready for consecutive MNK/NIN and THF type mobs...
Goal #2 -- Killing mobs ASAP. To get max exp/hour, not only do you have to keep the chain alive, you also have to kill the mobs ASAP. With puks you could use your pt and kill mobs very quickly. With higher hp mamools, Gravity and Dia 3 is NOT going to make up for another 800+ points of damage per fight (assuming that the 4th melee is even a piss poor one).
PT kills mob faster = More EXP per hour AND faster repops.
A couple of questions (you can lie on the answers, I'm sure you will):
In the North Mamool Camp, how far to the south do you go before you have to turn around because mobs have repopped in the small path to the north?
Also in this camp, when you return from killing the 3 Mamools + 2 puks that appear on the path and the small opening near the zone, how many mobs are up in the southern opening?
In response to the shadows issue, yes they will take damage. Its a TP-Burn party, so how could anyone be a "Careless Warrior" or an "Over-zealous" MNK. Besides WSing with 500hp left and no shadows, I have no idea how you could be careless in a TP-burn.
Again, you're just arguing to argue, and not reading my entire posts. RDM 'CAN' make it work, but WHM is more efficient because of what I said.
Freak accidents like too many links DO NOT HAPPEN after the first pull if you're killing fast enough. You're admitting how slow you kill if you are justifying using another mage JUST incase it happens. If it is happening, then gtfo of the North camp, and go party in mire with the rest of the people that shouldn't be wasting that camp.