IMO, large pulls are a bad idea in most instances right now. Not all; there are exceptions, but in most 51+ dungeons that I've run, when tanks try to mass pull it ends in trouble, or at the very least a large amount of stress.

Tanks are tending to be squishy now on large pulls, so I'm usually in panic mode trying to keep them upright (I've had zero problems with tanks doing small pulls). When I play BRD, I've lost or had nerfed most of my AoEs, so it's not like I'm more effective as DPS on large pulls than small. Flaming Arrow and Wide Volley are gone, Quick Nock sucks now except on low HP trash, and I can hardly spam Rain of Death.

If you pull small it allows the healer (and this is coming from a healer) to contribute to the DPS. If you pull large, the healer is doing nothing but spamming heals, and even then may need a SMN or RDM to help bail him out.

IMO, the changes they made to tanks (such as removing some cross class skills, changing the way the stats work), makes large pulling prohibitive in most, but not all, situations right now. I'm at the point where I don't even want to run roulette on AST or WHM unless I'm with friends, because it's too stressful.