[DeathsSilkyMist]

I did three new parses with my 60 SK on Shiel Glimmerspindle. 1000 hits each, just like my Shaman tests:

=========================
60 SK 1000 hits - 351 AC, Using 55 AC Shield
=========================
DV, Count
19, 541
22, 29
25, 26
28, 25
32, 29
35, 25
38, 27
42, 27
45, 26
48, 18
52, 22
55, 26
58, 27
62, 21
65, 25
68, 20
72, 27
75, 22
78, 27
82, 10

Total Damage = 33211

=========================
60 SK 1000 hits - 300 AC, No Shield
=========================
DV, Count
19, 453
22, 34
25, 36
28, 23
32, 42
35, 25
38, 26
42, 35
45, 32
48, 28
52, 24
55, 38
58, 27
62, 26
65, 33
68, 24
72, 29
75, 27
78, 32
82, 6

Total Damage = 35754

=========================
60 SK 1000 hits - 200 AC, No Shield
=========================
DV, Count
19, 291
22, 40
25, 33
28, 37
32, 37
35, 31
38, 39
42, 30
45, 41
48, 54
52, 53
55, 34
58, 54
62, 35
65, 31
68, 31
72, 41
75, 35
78, 37
82, 16

Total Damage = 41544

As you can see, the damage my SK takes is less than my Shaman. This is due to plate classes having a higher Softcap than chain classes.

I don't have enough AC on my SK to go above 300 without a shield, so I can't confirm the softcap is 300 AC for plate classes. But this data shows plate classes have a softcap of at least 300 AC.

Looking at my Shaman's data for 200 AC:

=============================
60 Shaman 1000 hits - 200 AC Test, No Shield
=============================

DV, Count
19, 289
22, 41
25, 41
28, 33
32, 32
35, 43
38, 43
42, 38
45, 40
48, 33
52, 38
55, 38
58, 37
62, 39
65, 33
68, 39
72, 41
75, 41
78, 34
82, 27

Total Damage = 41805

We can see that Shamans and SK's basically take the same damage at 200 AC in terms of damage taken from hits. This means the AC mitigation formula is the same across different classes. The primary difference between classes are the softcap and the softcap returns when it comes to AC mitigation. An SK would still take less damage in a specific time period (such as two minutes) compared to a Shaman, as SK's have higher parry, dodge, riposte, and defense skill.

Assuming my SK would take the same damage as my Shaman at 100 AC, it looks like going from 100 AC to 300 AC on a plate class reduces damage by about 48% on a level 40 mob like Shiel Glimmerspindle.