whats a good finish item for master yi build dps (zephyr vs trinity force)

I've finished a build but I'm stuck on the last item: hunter's to trailblazer berserker greaves bf sword to blood thirster phantom dancer (before infinity edge?) bf sword to infinity edge enchant trailblazer to devourer the black cleaver berserker greaves to (trinity force or zephyr?)

I have to account for movement speed, and attack speed but are the benefits worth the trinity force? The passive would take care of movement speed but I'm not sure if anything else really covers master yi. Also does your dps go up higher if you switch from an attack damage item (blood thirster 80 attack damage) to an attack speed item (pd). I followed that pattern but has anybody crunched the numbers.

Plus I think the devourer on ranger's trailblazer says it's supposed to be a %50 percent increase in attack speed but when I buy it, it only says %40. Is it really off or is that just a typo.

Thanks