When you crit, you get vengeance. Vengeance is 8 seconds. Doubling the crit chance more than doubles your vengeance up time. You notice having vengeance up much more. Seal of command, about 7 ppm, gives an extra "swing". You start noticing that attack crit more and going from 5 to 10% crit quadruples the chance of getting the auto attack crit SoC crit combo.
Doubling the crit is very noticeable. You can ignore it tho as I'm sure you will.