Berserking Vs Massacre Question

I've been looking around on wowhead and here trying to find more information on uptime for Berserking. I'm trying to figure this out so I may be really wrong with my thinking, but here it is.

From the posts I've read, it seems to be ~40%? And that the armor reduction is 25% per proc.

Given that, the effective AP of Berserking would be 400*.4 = 160 AP, though that spikes from 0 to 400 over the course of the fight.

This is a apples to apples 50 AP increase over Massacre.

Or 2-handed that would be 0-800 AP with and average of 320 AP or a 100 AP increase over Massacre's static 110.

However, apparently Armored to the Teeth calculations are done on a set interval, so if Berserking is proc'd during one of those calculations your AP from Armored to the Teeth drops.

I'm assuming 14000k Warrior armor for these caclucations because that's around where my guy is and even numbers make things easy to look at.

Assuming 14000k 2H titan-grip Fury Warrior, if the recalculation occured during 1 proc, it would be a drop of 97.22 AP:

((14000/108)*3) - (((14000*.75)/108)*3)

If dual-berserking and both are proc'd then a drop of 194.44 AP

((14000/108)*3) - (((14000*.5)/108)*3)

So there are three states for a 2-H Fury Warrior

1) Armor 100% at calculation - an average increase of 100 AP with dual berserking over dual massacre

2) Armor 75% at calculation - an average increase of 2.88 AP with dual berserking over massacre (100 - 97.22 loss in Armored to the Teeth benefit)

3) Armor at 50% at calculation - an average increase of negative 94.44 AP with dual berserking over massacre when factoring in the loss of 50% of the Armored to the Teeth benefit.

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Now most top-level players I've seen post recommend berserking, always berserking. But it would seem to me that, for 2-H wielding warriors that can almost always assume 1 proc up (is this a false assumption) the benefit to individual DPS is negligible and the increased strain on healers would make berserking less desireable than Massacre.

Now for all other dual-wielders it would seem that Berserking's average 320 AP versus Massacre's 220 constant would be desired, but factoring in Armored to the Teeth and I'm not convinced, and as armor increases there would come a point that even 1 proc of Berserking during the Armored to the Teeth calculation would mean that on average Berserking would cause a net decrease in DPS.

Are my assumptions wrong, am I missing something? Thanks for clearing anything up I may have had confused.