as baharoth said, when you get hit by 80k per shot, for example, blocking 4k only reduces that damage by 5%. dodge is A LOT better than block, anytime, vs anyone.
A storm shield has ~1000-1200 arm, 70-80ar, 7% vs elites, 6% vs melee which works vs sss and normal bells, maybe 150-200 vit or 16% life
so unless you find a 2 handed weapon with 1000-1200 vit , a 2 handed weapon setup will never be able to have the ehp of spear and shield, but definitely not because of block.
block is best vs fast small hits, vs big slow hits its effect is quite small.