When I mentioned the 5 man it was entirely as an example of every day every run stats, not a specific encounter to use. People may pug, pugs may never have a fdk, thus you can't always count on 20% haste, pug 10 man run may not have a blood dk with hysteria, do you get what i'm getting at here? you can only apply the stats you know you're going to have.
Armor pen has very little to absolutely minimal use for anything but autos, if I wanted to keep this going and take the bait for yet another reply I'd say something along the lines of regem to full arp and tell me that it matters.
Lets get some final things in stone because I'm done replying to this thread and I wanna leave something for other people curious about the spec that will do their own homework before blindly following what others say:
1) Sim your character, your stats are unique to you, find upgrades that are good for you, don't trust "BiS lists" or "BiS stats" because those stats or gear will not be exact each time and beneficial for you to get at that time, this does not mean those very stats do not become beneficial for you at a very later date, by all means use something like a Crit Cap calculator to see how close to it you can get before it becomes a problem same goes for every other stat value, 212 expertise is the goal to begin with to avoid being dodged, parried or glancing on your yellow (Mutilate, Envenom, Any combat point ability) after that, check each upgrade you get.
2) Guides and specs like the ones listed here may be out of date or completely false information, always read when the original post was created and ask yourself do bugs from 2014 still exist 4 years later after a core swap and all sorts of other updates to the game? likely hood no, which means something may change. Always do your own research before you commit to something.
3) Armor pen or ArP is not a fantastic stat, it is used for one thing and one thing only and that is your melee swing, do not waste time aiming for armor pen gear specifically if it is not a huge upgrade every other stat wise (Example: going from blue bracers to DBS 25 bracers.) DBW has a 105 second cooldown between forms, every other trinket in wotlk for rogues is a 45 second cooldown if it is a proc trinket.
4) Energy pool between envenoms, get 4 combo points, use envenom and mutilate to 4 combo points again, get 4 right away? great, let your energy go back up and watch your envenom buff when it drops off, cast envenom again and repeat until the boss is dead and you win the big game, go state.
5) 2 part t10 is more beneficial over 4 part t10 because if you're energy pooling like you should be above to maximise the envenom buff uptime you won't need another extra 4 or 5 combo points randomly since you already have a mutilate after you envenom lined up, it will leave you over capping energy and be a general waste of DPS or a global cooldown you could have used on anything else.
6) Don't trust people who tell you random factoids without any references or proof of the claim in writing, data or numbers (This applies to life too) there's too much misinformation out there and being misinformed about something is the single worst thing you can be. (Some smart *** will quote me on this and try and use it but go back a page and see all the references)
7) Use god damn Berserking, black magic is garbage, it is not worth it ever, mongoose is not worth it ever either, it's always going to be Beserking MH Beserking OH no matter what (Unless it's PVP), no it is not a DPS increase to have it in your bags and weapon swap it for the proc because re-equipping a weapon will trigger the internal cool down on Beserking meaning you've just lost out on 400 attack power (A small trinket).
8) The difference between stats (if you read the last two pages) at END GAME BIS GEAR is minimal at best, by a margin of .25 of a value between crit and haste, up until that point you may gain more from haste, you may gain more from crit, it really depends on YOUR stats and gear, that's why in reason 1 I said SIM YOURSELF.
9) This forum is a cesspool of toxic people looking for nothing more than confrontation and vindication on being "Right" in their mind, if you can't see that before you reply, you get trapped in a long long long post that does nothing between which they'll ignore the facts or side step them when asked about proof or evidence and bring up a completely different issue just so they can get the last word. -- Don't make my mistake, from 2011 until 2018 I ignored this forum and then I foolishly had to reply, never ever come back if you read this, I certainly won't be.