There's already far enough data, you don't need to theorycraft.
These were taken from random tanks that ranked around the 100th place in healing EX1, mitigation is calculated as well.

GNB 6.230HPS, 11% OH, ~5.630 effective HPS


DRK 5.600HPS, 6% OH, ~5.300 effective HPS


WAR 8.700HPS, 30% OH, ~6.100 effective HPS


PLD 7.500HPS, 19% OH, ~6.000 effective HPS


DRK is behind, that's true, but it's not apocalyptic either.