> On the other hand, Zephyr gives 50% more AS
Unless I'm missing something, are people actually getting zephyr on irelia right now as her "dps" item?
Like, considering the cost differences, the fact that one gives survivability (argue 35% tenacity over 45 MR) the only conceivable merit in building zephyr is because Stinger is similar cost to a recursive bow and provides much more "usable" stats. If you can afford a Stinger, then that's going to be giving you a spike which a recursive bow would not. If your argument/guide is one which compares the two items on her in terms of slot then I would assume most people would be aware that one is definitely going to be giving you more damage in a fight than the other.
So in other words, a guide for comparing the usefulness of the two items on Irelia really needs to consider the build path.