Originally Posted by Masterdragon

The point where ArP gemming starts becoming more over Agi gemming now requires a much higher passive ArP value without using either of the trinkets. Most gemming options that I've tried shows that gemming for ArP doesnt become a DPS increase until you near 800 to 900 passive ArP (i.e majority in Heroic TotGC gear). Also you other stats have a slight impact where this point falls but just getting one of the trinkets now doesnt mean you can gem ArP anymore, even when trying to soft cap for the 10 seconds the trinket is active. Granted that Arcane Shot is still dropped pretty early in the ArP curve. When the nerf to ArP came out, it kind of split the Marks Hunters into 3 categories instead of 2.

For Hunters less then 350-400 passive ArP, using Arcane Shot along with it talent.
For Hunters between 350ish and 850ish ArP, dropping Arcane Shot and using the ArP spec while continuing to gem for Agility.
For Hunters above 850ish ArP switching Agility gems to ArP Gems.

Of course you would still need to check out the spreadsheet values to see what gems would be most beneficial to you at your current gear standings. A full ArP gemming now pretty much requires you to be clearing TotGC and picking up the heroic forms of the gear.