So, I have some parse data and tests done for AC comparisons on my level 35 Erudite ShadowKnight while fighting dark blue/light blue mobs.
Damage report with 639AC
Code:
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DAMAGE TAKEN REPORT (AC)
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Data for 405 hits:
Breakdown (attacks done to you):
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Misses: 48.14814814814814814800
Dodges: 3.45679012345679012300
Parry: 2.46913580246913580200
Riposte: 2.71604938271604938200
Hit For: 43.20987654320987654300
Damage Spread (damage taken and how often it was taken):
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3 (25.1429%) 18 (2.85714%) 45 (1.71429%) 23 (1.14286%) 25 (0.571429%)
2 (16.5714%) 47 (2.28571%) 42 (1.71429%) 16 (1.14286%) 17 (0.571429%)
29 (4.57143%) 39 (2.28571%) 36 (1.71429%) 12 (1.14286%) 15 (0.571429%)
4 (3.42857%) 34 (2.28571%) 26 (1.71429%) 53 (0.571429%) 13 (0.571429%)
37 (3.42857%) 11 (2.28571%) 24 (1.71429%) 41 (0.571429%) 10 (0.571429%)
8 (2.85714%) 7 (1.71429%) 9 (1.14286%) 40 (0.571429%)
5 (2.85714%) 6 (1.71429%) 43 (1.14286%) 35 (0.571429%)
31 (2.85714%) 50 (1.71429%) 38 (1.14286%) 27 (0.571429%)
Averages:
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15.8171 damage taken per successful hit
6.83457 damage taken per swing (adding avoidance)
Damage report with 750AC:
Code:
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DAMAGE TAKEN REPORT (AC)
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Data for 338 hits:
Breakdown (attacks done to you):
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Misses: 47.63313609467455621300
Dodges: 1.77514792899408284000
Parry: 4.73372781065088757300
Riposte: 2.07100591715976331300
Hit For: 43.78698224852071005900
Damage Spread (damage taken and how often it was taken):
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2 (25%) 25 (2.7027%) 41 (1.35135%) 13 (1.35135%) 23 (0.675676%)
3 (14.8649%) 18 (2.7027%) 40 (1.35135%) 9 (0.675676%) 22 (0.675676%)
10 (5.40541%) 6 (2.02703%) 39 (1.35135%) 7 (0.675676%) 17 (0.675676%)
4 (4.05405%) 5 (2.02703%) 35 (1.35135%) 50 (0.675676%) 15 (0.675676%)
34 (4.05405%) 36 (2.02703%) 26 (1.35135%) 42 (0.675676%) 12 (0.675676%)
8 (3.37838%) 31 (2.02703%) 24 (1.35135%) 32 (0.675676%)
11 (3.37838%) 16 (2.02703%) 21 (1.35135%) 29 (0.675676%)
37 (2.7027%) 47 (1.35135%) 14 (1.35135%) 28 (0.675676%)
Averages:
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13.723 damage taken per successful hit
6.00888 damage taken per swing (adding avoidance)
And the comparison/averages:
In 750AC on average I was hit for 13.723 when hit (6.00888 per swing if you factor in those enemy misses/dodges/ripostes/parries)
In 639AC on average I was hit for 15.8171 when hit (6.83457 per swing if you factor in self avoidance)
The spread also seems much more favorable (less high damage spike attacks received).
Conclusion: As a level 35 Erudite ShadowKnight, 111 AC does make a noticeable difference when fighting dark blues/light blues.