Here is how different gear will affect your dps when you go from T15 BiS to T16 BiS for Assassination and Combat. From cloak upgrade and on it's assumed you have the previous mentioned upgrade.
T15 BiS when 5.4 hits live. (Assassination T15 2-set)
Assassination_256263.0 DPS
Combat_____245196.3 DPS
T16 Warforged upgrades
Cloak upgrade
Assassination 267131.3 DPS
Combat ___ _258488.1 DPS
Assurance of Consequence warforged upgrade
Assassination 271837.7 DPS
Combat _ ___ 292093.8 DPS
T15 HC 4-set -> T15 HC 2-set and T16 normal 2-set (Assassination goes from T15 2-set to T15 2-set and T16 2-set)
Assassination______________ __288109.8 DPS
Combat T15 4-set _________ __ 292093.8 DPS
Combat T15 2-set and T16 2-set _286526.7 DPS
Warforged Haromm's Talisman trinket upgrade
Assassination _ _ _____________292009.2 DPS
Combat T15 2-set and T16 2-set_ 291558.2 DPS
Combat T15 4-set _______ __ ___295740.5 DPS
T16 warforged weapons upgrade
Assassination _ _ _____________303945.0 DPS
Combat T15 2-set and T16 2-set_ 307663.0 DPS
Combat T15 4-set _____ ____ ___311633.5 DPS
T16 normal 4-set + T16 off-piece (bye T15 4-set)
Assassination _ _ _321316.0 DPS
Combat T16 4-set _326894.6 DPS
Combat T15 4-set _317371.6 DPS
T16 warforged offset item upgrades
Assassination __ _339874.4 DPS
Combat T16 4-set 347755.5 DPS
Combat T15 4-set 340224.8 DPS
T16 Heroic Warforged upgrades
Assurance of Consequence warforged upgrade
Assassination_____344579.7 DPS
Combat T16 4-set _355562.8 DPS
Combat T15 4-set _350002.5 DPS
Warforged Haromm's Talisman (A) and Ticking Ebon Detonator (C) trinket upgrade
Assassination______351962.8 DPS
Combat T16 4-set _ 360402.4 DPS
Combat T15 4-set _ 356290.3 DPS
T16 warforged weapons upgrade
Assassination _____364928.7 DPS
Combat T16 4-set _377966.5 DPS
Combat T15 4-set _374023.0 DPS
T16 4-set -> T16 HC 4-set + T16 HC WF off-piece
Assassination________ 388493.5 DPS
Combat T16 HC 4-set _ 394879.4 DPS
Combat T15 HC 4-set _ 378937.5 DPS
T16 warforged offset item upgrades [BiS]
Assassination _____414426.8 DPS (by Dextar)
Combat T16 4-set__414457.9 DPS
Combat T15 4-set__401483.1 DPS