4 piece bonus with only 384 pieces will be around 800 upgrade for Arcane and about same as 4x391 t12 for Fire.
Mainly that section, with the main question underlined.
The question I have is how do they find its the same? The way I read that is if you had full 391 t12, it will be roughly the same DPS as full 384 t13.
I opened up the lastest version of RAWR, and ran a Sim in my current gear. It told me to keep my current gear (378 helm, 378 gloves, 391 pants.) I have a 391 t12 tier chest as well, but replaced that with the 397 t13 chest (again, used RAWR). The test I did where including my 397 t13 chest and 3 other 384 t13 pieces.
Is RAWR not counting in the set bonuses yet? Or is what Paragon originally stated wrong and just hasnt been updated? Or did I just understand the above quoted wrong?
TL;DR: I have 4pt12 (1 piece 397) and 4pt13 (1 397, 3 384s) and paragon said it would be the same DPS. I used RAWR to sim it, and I got a drastic DPS drop if I equip the 4pt13.
Thanks for your help in advanced! And go go paragon for #1!