Haste from percent-based buffs does stack multiplicatively with each other and with total haste from gear, so if you have 20% haste on gear, IIT, and raid buffs, you have 1.2*1.05*1.2*1.03 for a total of 55.7% haste. This is quite easy to see since such buffs are reflected on your paper doll swing speed (though I admit I've never done or seen any tests to verify that the paper doll is correct).
The haste formula is
I have 6.11% personal haste, with 5% from IIT that would be 11.11% haste if it stacked additive, or 1.0611 x 1.05 = 11.41% if it stacked multiplicative.
2.34 or 2.3335, my listed weapon speed 2.33, so you are apparently correct, thanks.
I have redone some calculations with the following corrections: added increased haste, added glancing blows, assuming that crits can become glancing and crit chance is thus reduced by glancing chance and I added 3% crit from Annihilation to specials that I simply forgot.
I don't want to edit the main post so people know what the things written here are about, so I'll just write the new results:
Assuming 40% haste (for simplicity) we get 1.79 dps per weapon dps (without BCB, 2.01 with BCB) and assuming full subversion we get new values of 2.72 for obliterate, 1.06 for BS, 0.90 for PS and 1.76 assuming now 60% for FS, I still don't know if that's a reasonable number, but it's higher than the previous one at least, even if you consider Annihilation. Totalling that makes 1.05 instead of 1.02 per avg weapon dmg.
Firstly, normalization only affects AP scaling, IE the forumla to calculate an Obliterate's damage is (AP/14*2.4+weapon damage)*25% assuming two diseases. The 2.4 in the parenthesis is the normalized number, instead of the weapon's actual speed.
That is correct, did I state anything different?
Secondly, looking at current parses, strike based mechanics fill up roughly 50-60% of our damage (Obliterate, Blood Strike, Plague Strike, BCB, Frost Strike) while white attacks do around 25%. I don't see how it would be a DPS upgrade to boost white dps when strikes do twice as much of our damage and are heavily reliant on weapon speed due to the multipliers involved.
Going by percentages of damage is not an adequate way of understanding this.
If you want an "easy" way of understanding, consider this:
On a very basic level, in order for 1 point of weapon damage to be equal to 1 point of dps, you would need to strike every second, but you don't. The higher percentages of strikes has 2 reasons:
1. They scale better with AP, you strike more than once every 2.4 secs, but AP treats it as a 2.4 sec hit, this has absolutely no impact on the calculation per weapon dmg point.
2. Strikes have static modifiers, people tend to underestimate those since they don't scale, but let me assure you that +1000 static damage to obliterate is very significant especially for DW, again this does not influence the calculation.
Obviously, trying to find the exact numbers after considering this is exactly what I wanted to do.