There is an official site that talk about block value cap ? or when DR is on ?
I have a trouble with my guild, cuz I insist that Block isn't the best ability and they keep saying that I have trouble of block and my char need more block.
I see a lot of topics here but nothing that points to and official link :S
I think that the most that you can block is 3k of damage, I don't know if I'm ok ;S
Block will not get a cap with 3.2. The only thing that will be capped is the maximal amount of dmg (and thread) one will be able to do with a given rank of shield slam and the paladin version of it. Which is weird enough since it will be the only signature dmg ability that will NOT scale if you reach some given item values (it will stop to scale with BV very fast if you try to stack it).
None the less - block is a bad thing to focus on if you do more than trash tanking (and even than you have to consider if you really want to be rage starved then or want to get at least some rage together with minor dmg). Block value on items (not shields) will be doubled with 3.2. Additionally you will be able to get more rage from blocks and avoidance with 3.2. So block may be a nice stat for trash groups then. But even with that buff will stay weak against bosses.
So if you want a quick answer for boss encounters: Try to stay away from block if you can get other stats. Block rating is worse than block value for warriors. Every other tanking stat will give you more for your survivability.
Ask your guild what they would prefer: That you have a 2% higher chance to only be hit by 18k instead of 20k or that you have a 1% higher chance to not be hit at all. That is the kind of decision you make if you take block.