nope, because I don't have the time to dedicate to beating all of the dungeons as soon as they come out. I have a real job and don't live in mommy's basement. When I am logged in, I do a lot of things to help players in my shell get what they need to accomplish their goals. I help with AF quests, moogles, ifrit, darkhold, HD, stronghold bosses, etc. whenever needed, am currently in a garuda static as well. The bottom line is, I haven't really tried AV. Lodestone achievements are not an indicator of skill. You'd be hard-pressed to find anyone I play with that'd say I'm not a skilled tank.
When you are comparing materia in this way it's probably best not to compare a perfect tier IV to a tier I. I'm not even going to answer this.
tier I bloodwall (DEF) range from 2-8
tier IV VIT (10 block power 20 hp and magic mitigation) range from 16-20
Now, if you want to compare apples to apples, 20 DEF to 20 VIT (10 block power 20 hp and magic mitigation), it's kind of a wash. But if you want bang-for-your-buck in a single area, 20 DEF has the most affect in any one single area, physical def. You don't use the 10 block every time you get hit, only when you block, so it's usefulness is negligible. Also, bear in mind that quite a few of your blocks are due to using aegis boon. When you're getting cured by blocking, damage mitigation from blocks isn't very important. It'd be interesting to see how much DEF, 10 block translates into in terms of physical damage mitigated, I'm guessing the number is close to 10 def. but that would be 10 DEF every hit blocked instead of 10 def every time you're hit.
As Kaeko pointed out, damage mitigation when looked at in terms of usefulness in a party is negligible as well because of WHMs healing power. So in my opinion, it's better to focus on a single area (physical damage mitigation) then spreading the benefit across several different damage mitigating stats.