First, let me say that this question is on the use of the talent Serrared Blades and not the increase damage to rupture or its use in Hemohrrage.
What I want to know is, is this talent viable for rogues in PvP and PvE without being Hemorrhage spec'd? With new gear ignoring armor is this now more applicable in PvE? In PvP is the armor negated worth spending the points without going into Hemo?
I did do a search and found almost all the threads had to do with Rupture and not the armor negation of the talent, sorry if I over-looked a thread where this is answered.
The nice thing about armor penetration is that the more you have, the better it is (to 0, at least, but I'm coming at this from a PVE standpoint). It's not a huge amount of armor that it's ignoring though, so JUST getting this talent for the armor penetration doesn't seem like it'd be stellar. You should be using rupture in PvE at least, however, so if you're up to that point in the tree, I can't see it being a bad investment.
The major point you fail to address is this: What will you get instead of this talent? "Is it worth it?" isn't a good question unless we know what you're giving up for it.
It's a perfectly good talent and if you're 15 points into subtlety anyway, it's probably worth taking. Of course, I'm not sure why you'd be 15 points deep in subtlety *unless* you were going for Hemo (or a deep-sub dagger build, I guess). As noted in the preceding posts, typical PvE specs have either 0 (swords/fists/maces) or 5 (dagger) points in subtlety.
Long story short? It's a nice talent for subtlety rogues, but too far into the tree to be useful for combat or assa builds.
The major point you fail to address is this: What will you get instead of this talent?
Sorry for not making this clear in my original post. What I mean is, is this talent worth going into the sub-tree if your going to be raiding? Or is it possible to have this talent and still have a viable PvE spec?
In PvP with alot of rogues going mutilate spec is it a good idea to get this talent when there are others(eg. Imp Ambush, Elusiveness etc..) that are also good to have?
Mutilate/Combat (41/20) will output more DPS than Mutilate with Subtley spec, even with Serrated Blades.
But, if you want a PvP Mutilate spec, you already have some points in Subtley, so why not take Serrated Blades as well.