This is how I think about it. I used to play a pally healer, I rarely ever didnt overheal 500-1k each heal, so basically if that tank had had 500 less BV it wouldnt have made any difference from a healers perspective. In this current game healers bomb large heals, taking 1k less dmg per hit isnt going to make a huge difference to them, however dodging 2-3 straight hits will make their life a lot easier. I wear 1 item with block, my shield, and unbuffed I am running 28% dodge, 19% parry and around 14% block, full raid buffed taht puts me right around 102.4%, so I rarely eat a full hit, and when I block I block for around 1700.

By stacking block rating and value you probably have less dodge/parry then me, you are probably over 102.4 and you may block 3k of each attack, that 1300 extra block isnt often going to save your life, however dodging an attack will often save yoru life.