Wound vs Instant poision

Because Z prompted me, I did the very awful math behind Wound and Instant poisons and he is correct.  But to elaborate on his point, if you do not have 5/5 Improved Poison in the Assassination Talent tree then Wound Poison is always better than Instant.  If you do have 5/5 Improved Poison then use Wound Poison until you have 2500 AP, and then switch to Instant.  The math is below in case number people like me want to see the break down. 

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Wound poison VII has a 50% chance of poisoning the enemy, causing [231 + 0.04 * AP] Nature damage and reducing all healing effects used on them by 50% for 15 sec.

Instant poison IX has a 20% chance of poisoning the enemy which instantly inflicts [300 + 0.10 * AP] Nature damage.

Wound VII: (231 + 0.04 * AP) * 0.5 = 115.5 + 0.02 * AP 

Instant IX: (300 + 0.10 * AP) * 0.2 = 60 + 0.02 * AP 

5/5 Improved Poisons- 0.01 * AP > 115 - 90

Wound VII: (unchanged) = 115 + 0.02 * AP 

Instant IX: (300 + 0.10 * AP) * 0.3 = 90 + 0.03 * AP