If you are worried about blood survivability. Don't be.
VB is a very very powerful ability. Apply it with mark of blood and some well placed rune taps and you can survive most boss enrages for an extremely long time.
I've said it before on here and I'll say it again.
My blood threat is insanely high and I can pull off just about any tanking class, one our second time killing patchwerk I was assigned to be a hateful tank along with our guilds MT, sticking an unholy DK in lesser gear as the MT.
Couple seconds into the fight I pulled off the MT and started to tank him, while the other tanks tried to cope with my little goof. about a minute after I pulled the warrior went down then the would be MT. He proceeded to pick off our melee leaving me the only one left in range. Three minutes left until the enrage with me using every CD I had I tanked patches melee and hatefuls for three minutes until he enraged.
You may not have 100% avoidance with CDs like frost, but you dont even need it with the amount of health and self healing you have.