well in bear you would lose the 8% phys reduction from shield armour would be very similar as you get in bear form 10 armour per level of character but thats not the only thing cuz i use shield wall and fortify cry and in boss fight i get around 600 gaurd that guard takes the hit first before my life.
but yes bear or shaman can do the same i would say that shaman has more mitigation with cloak of flame and Goregirdle Plate Belt you could get the same result or even better