Okay KBN, I've been trying to see where some of our differences might be coming from and I see a few things that could be related, although, our calculations are exactly the same for Guardians/Juggernauts and there is still some difference, which probably has to do with the way I generate the numbers.
I first verified my mrke and ftke values matched what you have in your formulas, I actually rounded up, but just to be precise I followed your double digits after decimal. I then verified that we were both calculating mrke and ftke damage correctly, taking into account the 2 roll system ect. And found my numbers matched what your numbers said based on the formula you posted.
Next was the base values, and that is where I see a bit of difference. As I said, the Guardians/Juggs seem to be the same, Shadow/Assassin are close, only difference is your calculation for absorb bonus from dark bulwark is slightly higher than mine, but they were still close. Vanguard/powertech is quite a bit different though and so this is where the big shift changes I think when i've been comparing numbers (since powertech is my main), so I wanted to pick your brain and see why you did what you did. Maybe I'm overthinking it.
Here is the relevant part in your base calculations.
So looking here I see you are adding 0.075 defense because of Oil Slick (Riot Gas for you pubs), which is cool, it's pretty straight forward, I came to the same conclusion, 30% for 15 seconds every 60 seconds, averages 7.5%. Now where this gets me though, is you also have the 0.02 for resist, which tells me you are assuming they have the 4 piece set bonus. If they have the 4 piece, that means they should have the 2 piece as well, which gives Oil Slick/Riot Gas 2 more seconds, which brings it to 30% for 17 seconds every 60 seconds, average of 8.5%.
Next is the Absorb Bonus, which I assume is from Heat Screen & Heat Blast (Power Screen & Energy Blast for pubs) I did a bit of research on this and saw you and Dipstik had different theories on this...and so well, here's mine. Anyway, the way it works is you generate up to 3 Heat Screens, each of the screens gives 1% absorb for 20 seconds. Once you have 3 stacks, you can spend them to activate heat blast, which grants you 25% absorb for 6 seconds, on a 15 second cooldown, however, each stack of heat screen lowers this cooldown by 1 second, so you can pretty much use it at best about every 12 seconds. So I personally count the heat blast as 12.5% (25% for 6 seconds every 12 seconds) Now the heat screen is tricky since it is consumed when you use heat blast.
Technically you wouldn't get the 3% benefit for long because you should be using it as soon as you get the 3rd stack. I've searched my own logs and see that I average a heat screen every 4 seconds during most boss fights. I average them out to 1.25% bonus absorb. How you get 16.33% has me stumped, even if I did 12.5+3 it would still only be 15.5, to get close to your number I have to average 3 seconds per heat screen with a +3% constant, not accounting for them being consumed.