Okay I've done some calculations, replaces power augments over mainstat turned out less dps on the dummy run 6 parses on each augmented gear. I was 4.4 with with mainstat and 4.1 power augments. This is in serenity/hatred. I'm yet to try alacrity, currently off shore. But there is someone that has posted results of it on the guild forum. They did 6 parses and averaged 30dps more with alicrity augments but I would disagree with full alacrity augments. I would maybe 50/50 mainstat and alacrity, not tested yet but will post results.
For deception/infiltration I personally have 2 alacrity power enhancements but everyone has different Prefences.
Just because of DM but I wouldn't hesitate going over it for pvp. Plus it's nice having surge in the 204 mainhand for pvp. Hitting 14-16k mauls on nabs in pvp is fun.
Theres always hate on people that try get gear stats across to people but I mean as long as you have your basic stats almost there then everyone can have whatever they feel like is right for there play style. Like a lot of people still don't use acc for pvp when I would at least get 105% for the 5%defence chance on all players. Yet people disagree just go with what you think is best or just do what I like to do, test numbers test gear and find out what's best for you
But, back on topic
I'll run full alacrity and 50/50 alacrity mainstat and post numbers if someone doesn't do it before me.