With the upcoming nerfs to bonesheild and to a lesser extent ice bound fortitude AND the buff to Vampiric blood (last stand effect added as well as 10 second increased duration via glyph) I think that VB is now the strongest tanking cooldown.
VB has higher up-time than boneshield on all but the most geared avoidance tanks. I'm not sure how the math works out but +50% to incoming heals for 30 seconds of every minute seems like it would be compare favorably to 20% damage reduction for a minimum of 15 seconds ( more if you have good avoidance)
This is also not taking into account the + 20% max health during those 30 seconds which of course gives your healers a buffer for overheal as well as a health buffer to prevent gibs.
The 20% max health synergies well with a talented and glyphed rune tap for some massive OH S*** buttons. I have read some anecdotal evidence that is showing rune tap hitting for almost 9k fully talented and glyphed on a geared MT with Vampiric Blood going.
What do you guys think?