Ive been surfing the net, and various hunter forums on enhancing your hunter dps. My question tho is on gemming your gear. From what i can tell, doing +20 agil gems on everything (and one prismatic to get your meta gem bonus) is the way to go, but only for a while. What i herd was that once with your gear, when you reach a ~400 arm penn rating, you want to switch all those gems out with +20 Arm Pen Gems. By doing that, the outcome of having more armor pen then agil will make your dps higher. Is this true???
It's like understanding the difference between thEn and thAn. Just because they sound the same doesn't mean you should always write "then".
So it is with ArPen; so I'll give some pointers...
ArPen affects physical damage; so SV hunters gain much much less than MM hunters (or physical melee dps classes for that matter).
ArPen is governed by a soft cap and a hard cap (beyond which additional ArPen is totally wasted).
One way of going about this is to get soft cap with gear/gems and use an ArPen trinket to push for the hard cap. (This was essential with Uld gear, but it may be possible to forego the ArPen trinket with ICC gear.)
That said, the raw numbers show that MM can achieve great dps; note that this is from a purely theoretical point of view.
From a practical point of view most raid fights require a lot of movement which limits Steady Shots (which has cast time), and reduces auto-shots. Since this is a sizeable chunk of physical dps, the practical effectiveness of ArPen is reduced.
Some hunters prefer to keep things simple and stick to AGI in case their off-spec is more suited to a particular fight.
On a side note; I saw you have 423 hit rating! You do know that anything over 263 is a waste? (230 for a Draenei)! If you do go the ArPen route - understand it first! - don't overdo it!
---- PS: As for then/than: thEn is used for time relations. For superlatives use thAn. E.g. "more armor pen thAn agil"