Eh I think even in physical dmg heavy raids so far not a single fight made bringing pld better than drk. The extra healer dps afforded by the extra physical mitigation doesn't outweigh the dps difference between similarly geared drk and pld. As of now drk/war is the optimal composition in every floor of savage despite a9s-a11s tank dmg being mostly physical. Pld MT in physical dmg heavy fights would definitely be easier to heal, but not optimal.