ArP and You
Do not gem ArP unless you meet one of these requirements.
1. You have a trinket that proc's ArP
http://www.wowhead.com/item=50198
http://www.wowhead.com/item=45931
http://www.wowhead.com/item=40256
When you meet this requirement you will gem only enough ArP so that when the item procs you sit at 100% then you will pop CD's during the proc's up-time.
2. Your gear can sustain levels of ArP meeting or exceeding ~85%
The exact point ArP outweighs strength is different per character and class but the point is below 85% in the majority of cases.
So in the mean time Gem strength it is a much nicer amount of DMG than you will see with ArP right now
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