I put together a quick spreadsheet to work out what damage reduction you get from [spell]unbreakable armor[/spell]. In my gear, approximately, I’d take 13.5% less damage when it’s up than with just base armour in frost presence. It would be 15.8% if it was glyphed too.
I’m thinking of going to Frost for ICC, since so many bosses suit a physical damage reduction tanking style. I’m currently Blood. I’ll probably go into [spell]acclimation[/spell] too, two-handed, two disease. I will carry around a spare stack of glyphs for howling blast, frost strike and UA to swap around for heroic 5-mans or boss-tanking.
My dps off-spec is unholy.
Download the Excel xls here.
Anyone else having thoughts about changing their primary tank spec?
Update: the comments are particularly worth reading.