Hab mal dise Antwort zu einem Thema in VN Boards verfasst und dachte evtl. ist das von Interesse.

Here is my take:
A)
I think that the TOA and Frontiers resistances are factored like this:
resulting damage =
raw damage
* (100-item resist)/100
/ (100+RA resist)/100
/ (100+TOA resist)/100

Example:
100 * 0.76 / 1.28 / 1.10

For Physical Defense and Avoidance of Magic this results in:
base damage: 100
minus base resist: 74 -> 1.35
minus 74/1.28: 57.8 -> 1.73 => 0.38

reduction with base resist and PD5: 42.22%.
PD5 gives you an extra 16.2% damage reduction.

Assuming a 2000 HP Hunter:

12% resist -> 0.136 => 272 HP virtual
19% resist -> 0.258 => 516 HP virtual
28% resist -> 0.380 => 760 HP virtual

virtual HP / RA points = HP per RA Point
272 HP / 20 = 13.6 HPpRA
516 HP / 40 = 12.9 HPpRA
760 HP / 68 = 11.2 HPpRA

B)
Toughness
25 HP / 1 = 25 HPpRA
75 HP / 4 = 18.8 HPpRA
150 HP / 10 = 15 HPpRA
250 HP / 20 = 12.5 HPpRA
400 HP / 34 = 11.8 HPpRA

C)
Doc_McAlister
Aug Con (rogues get 3.25 hit points per point con).
1 - 13
4 - 39
10 - 71.5
20 - 110.5
34 - 156

13 HP / 1 = 13 HPpRA
39 HP / 4 = 9.8 HPpRA
71.5 HP / 10 = 7.2 HPpRA
110.5 HP / 20 = 5.5 HPpRA
156 HP / 34 = 4.6 HPpRA

D)
Assuming a 2000 or 1000 HP Hunter:
IP 25% 500 HP / 5 = 100 HPpRA
IP 25% 250 HP / 5 = 50 HPpRA

IP 50% 1000 HP / 15 = 66.67 HPpRA
IP 50% 500 HP / 15 = 33.33 HPpRA

IP 80% 1600 HP / 30 = 53.33 HPpRA
IP 80% 800 HP / 30 = 26.67 HPpRA


The Hitlist for the most anti bang for the buck:

100.00 HPpRA : IP 25%
66.67 HPpRA : IP 50%
53.33 HPpRA : IP 80%
25 HPpRA : Toughness 1
18.8 HPpRA : Toughness 2
15 HPpRA : Toughness 3
13.6 HPpRA : PDef3+AoM3
13 HPpRA : Aug Con 1
12.9 HPpRA : PDef4+AoM4
12.5 HPpRA : Toughness 4
11.8 HPpRA : Toughness 5
11.2 HPpRA : PDef5+AoM5
9.8 HPpRA : Aug Con 2
7.2 HPpRA : Aug Con 3
5.5 HPpRA : Aug Con 4
4.6 HPpRA : Aug Con 5

Note that this is only valid if you dont get healed (soloing).
If you are in a gank group ( and I think Hunters will be more often in groups now with True Sight and Volley)
then resistances become more important to reduce healing demand and HP becomes less important.

http://vnboards.ign.com/Midgard_Rogue_Professions/b20912/69025538/p2/?33