When i have tried Dex it has never worked for me SB, and too be honest if you are getting the astral armour now, that has defense bonuses incorporated, so focus on vitality; 5,5,5, rest, although if KS does occur on your server add a bit of strength on there to prevent it happening to you. I'm mixed and can tank and hit hard; 125, 5, 5, rest and my hp are around 3k and i dodge some boss hit too..
If you dodge with astral, then you will dodge a lot more with dex. If you don't like dex, that's fine. What I find is that if you play long enough with dex, you won't notice how useful it is until it's back to 5.
I put full strength for a while once. I hit hard, but I missed a lot compared to the times I had dex. Missing may not be a big deal but the dodging and blocking is very handy.
Personaly, I think 3k health is a bit much in any situation:
-soloing a harbinger with a few pots. Less pots are used if you dodge
-tanking a boss that hits 200's fast with a Druid that heals 500. You are losing more health than you are being healed, so dodging can potentially buy you enough time to refill your health.
-your role is to attack a boss. Miss, miss, miss, miss? Or Hit, miss, hit, hit?