So, if full parry gave you 2%, it would be equal to having an extra sentinel to pop over time. More, this would amount to a 20% increase in total dr over time (2% added to the ~10% from abilities.) so yeah.... It's pretty cool even at this low value.

Not to mention my own testing on turn 5 pre 2.2 has agreed with Casper's value. The returns are very high.

Where parry shines is on big hitting mobs in very strenuous situations. Having so much parry made me able to solo tank twin, which was the only way my group could win. Continuing to have it is allowing us to solo tanking turn 6. Those percentages add up. In places like 5 and 6, in many ways the auto attacks are more dangerous. You don't get killed by the 8 stack cleave, it's the AA after it that drops you. High parry and block gives you a strong statistical chance to mitigate and live in danger situations.

Ps: @50 parry = 1% dr, I'm at about 620 atm. Aka 12.4% Aka more than my entire cool down suite.