Hi, for my brother hunter's in the clan I have done some calculations into when +AGI > +AP based upon what your dps will be. Using the following formula's involving rap/crit/agi/dps (these can be found on the net, I'm too lazy to find a site to link):
14 RAP = 1 DPS
1 AGI = 1 RAP
40 AGI = 1% Crit
Now, say if you are choosing between a +16 AP gem or a +8 agi gem, and your DPS is X, the overall DPS change will be:
+8 AGI --> (8/14 + x)*(1 + 8/40*0.01) - x ~= (0.57 + x)*(1.002) - x = 0.57 + 0.002 * x
+16 AP --> 16/14 = +1.14 DPS
Since the average damage added by crit is dependent on you current DPS, the higher your DPS is, the more crit gives you, so, solving the equation formed by equating the 2 above equations yields:
1.14 = 0.57 + 0.002 * x --> x = 285.14.
In other words if your DPS is above 285.14 - Choose an AGI gem/enchant over AP gem/enchant, it will increase you DPS more overall.
Of course this point will be lowered if you have the Lightning reflexes talent in the survival tree or the Combat Experience talent in the MM tree.
--------------------- Added Calculations for Crit rating / AGI ---------------------------
Run and hide now!!!! Even more math!!!
After I did the above post I started to think - what about +crit?
So what about + crit? +22 Crit = 1% crit
Performing similar math as above, comparing the +8 crit vs. +8 agi:
+8 crit --> 8/22*0.01* x = 0.0036 * x
So equating the agi to the crit equations:
0.0036 * x = 0.57 + 0.002 * x --> x = 349.9
Which means that if your DPS is about 349.9, you go with the +8 crit gem as opposed to the +8 agi gem
But where does that put +AP vs + crit?
0.0036 * x = 1.14 --> x = 314.3
So overall DPS gain, go with +AP until 285.14, then +AGI until 349.9, then +CRIT for optimal gains. Again talents that make AGI scale will widen the gap for which agi is better.
-------- Yet another Edit, Added a way to determine if your new gear will improve your DPS over your current gear ------
Just to make this a little more complete, here is a way to calculate if your new gear is better than your current gear, only taking into account AP, AGI, and CRIT into your total DPS gain. Note that this does not include other essential stats such as MP5, int, stam, etc, as well as talents and procs.
Let dAP = (new gear's +AP ) - ( current gear's +AP )
Let dAGI = ( new gear's AGI ) - ( current gear's AGI )
Let dCRIT = ( new gear's +CRIT ) - ( current gear's +CRIT )
Let x be the current DPS with the current gear.
so the gain in crit% is: dC% = (dAGI/40 + dCRIT/22)*0.01
and the gain in RAP is: dRAP = dAGI + dAP
which yields an average DPS gain of: dDPS = (dRAP/14 + x)*(1+dC%) - x
If dDPS is negative, then your average DPS will be lower in your new gear, if your dDPS is positive, than your average DPS will increase with your new gear. I hope that others will find this useful.
*** edited to fix some signs (whoopsie) ***