So much this. I run deep prot and I really only lose aggro when I get unlucky with misses and parries on my sunder.
Thing is, the prot tree is kinda weird. while the fury and arms tree CLEARLY offer dps, Prot doesn’t obviously give you mitigation or threat aside from shield slam, deeper than the defiance and shield block talents at least.
What is DOES give you is better Oh Crap buttons. Taunt is up more often, concussion blow is effective snap cc, imp sunder can pile sunders quicker, shield slam is snap threat that doesn’t rely on taunt, shield wall lasts longer to let people recover.
In short, a fury tank is for an extremely consistent, well run guild that doesn’t mess up and pushes numbers to the max. Deep prot is for basically everyone else.
/personally, I think most raids could benefit from at least one tank of each type, but that’s just me.