Some (Prot) DPS gear decisions

[Naka]

While i didn't have any luck so far to pick up either Commendation of Kael'thas or Shard of Contempt or even one of the blue expertise-items on normal mode, at least i got two new pieces for my DPS set: Netherforce Chestplate and Sunstrider Warboots.
Now, i'm a tank and i know how to compare tanking gear (at least i think i know :p), but i have difficulties to compare these dps pieces to my old stuff, especially regarding the armor penetration.

So, i'd greatly appreciate your thoughts about

Netherforce Chestplate vs. Bloodstained Elven Battlevest
and
Sunstrider Warboots vs. Ironstriders of Urgency

My DPS gear isn't that great alltogether, my unbuffed stats in the old gear are:
535 Str
155 Agi
1468 AP
170 hit rating (10.78%)
16.27% crit
11 expertise
21 haste rating
161 armor penetration
MH: Spiteblade /w Executioner
OH: Fury /w Potency

[Shortypop]

I'm in a fairly similar position having got the same breastplate yesterday (and was wearing the ZA one) like yourself. I decided to gem and chant to new one, mainly because I remember someone somewhere saying that for armour pen to be useful you needed a fair amount (no idea what this means) of it, and the breastplate was my only piece. So at the moment its in my bank. But like you some guidance from someone who knows more about this than me would be wonderful.

My stats (with old breatplate) were:

575 Str
152 Agi
1694 AP
162 hit rating
29.01% crit
10 expertise
0 haste rating
161 armor penetration
MH: Decapitator /w +20 strength
OH: [Fury] /w Mongoose

[Taelas]

ArP gets better the more you have of it.

I'd pair your old breastplate with your new boots and call it a day.

[ebs2002]

You could always go by the age-old "what's the i-lvl of the item" test. Neither of those drops are an increase in ilvl over your old one, so I'd say that neither are really worth the upgrade.

However, what you COULD do, is use the prot dps sheet posted elsewhere on these boards, and see what the difference would be with each configuration, and go by that :-p