This was a post I made at EJ; I figured it might be of value to a more general audience.
On a side note, I do apologize for not posting more. The honest thing is that I simply don't have a lot to say. I don't like to post about encounters I've not done, and I haven't raided in weeks (and will likely not be doing so for the foreseeable future). I will have the loot lists ready fairly soon, but they're not so compelling for me to get them done as they don't really affect me. If you have questions or would like me to research something or check something out, let me know.
But it's more likely that this blog is going to be done.
Anyway, on to the post. The preface is simple: what are the best T8 items to keep for the 2pT8 bonus for cats? This assumes you're aiming for (eventually) getting hard-capped on armor pen and going for as much as possible. If you're not, your priorities will change.
The best items to keep in general are the shoulders and the gloves simply because of itemization costs; they have the least itemization value, so you lose less when staying down. But let's go through each one, comparing T8.25 to T9.25:
T8 gloves vs T9 gloves: lose 8 agility, stamina, 5 AP 57 hit and 66 crit. Gain 43 armor pen, 33 haste. The big gain here is in hit rating, which I've found to be everywhere. This is a good place to start on T8. (note that while the ilvl differs, the itemization between the T9, T9.25, and T9.5 gear is the same, so you'll be losing the same kinds of things).
(note that while the ilvl differs, the itemization between the T9, T9.25, and T9.5 gear is the same, so you'll be losing the same kinds of things).
T8 shoulders vs T9 shoulders: lose 16 agi, 27 stam, 23 AP, 59 armor pen, 67 haste. Gain 48 expertise, 62 crit. This is one of the better slots for T9 with the armor pen, especially if you can afford to lose the expertise or don't care about it as much.
T8 head vs T9 head: lose 38 agi, 14 stam, 15 crit, 74 expertise. Gain 50 armor pen. This is one of the few pieces of T9 gear with expertise, but the T8 head does have that armor pen. The agility loss is big, though also note that the socket is red in the T8 helm, making it even better in terms of bonuses gained (either another 8 agility or more overall armor pen, depending).
T8 legs vs T9 legs: lose 6 agi, 14 stam, 35 AP, 20 crit and 74 hit. Gain 50 haste. Neither are particularly well-itemized for ferals, but the hit rating may be problematic for the T9; if you're close to the hit rating cap these are probably another good choice for T8 given the small differences in overall itemization. Note that the non-tier piece from Coliseum only swaps crit for haste, so it's not any better.
T8 chest vs T9 chest: lose 23 agi, 17 stam, 19 AP, 18 crit, 80 haste. Gain 49 hit. This is basically a clear upgrade from T8, but doesn't have the wow factor of pieces elsewhere. This is also a situation where the off-tier piece is clearly superior in general to both; [Vest of Shifting Shadows] is much better than either tier piece due to the armor pen and the extra socket, as is [Knightbane Carapace].
Based on the above, I would keep the T8 gloves and oddly the head, and go for the T9 shoulders first, then the legs.