well using the formula from the wiki you get this: ((DMG*2)+DMGBONUS)/DLY
the dual wield formula seems a little less certain i think but at lvl 50 I think your offhand attack occurs about 65% of the time and has no bonus damage.
Harder to quantify are considerations like ripostes. You take less riposte damage with a 2hander and also deal more riposte damage.
so at lvl 50 you have these dps "ratings"
mith 2hander: 15.63
with FBSS PSD + EBW: 17.87
w/o haste PSD + EBW: 14.77
attached is a spreadsheet that I made for myself to compare some of these things. Its not super user friendly and i'm not really offering tech support but you can take a look at it if you want. Its possible that its incorrect but I used the best formulas and assumptions I could find.
https://docs.google.com/spreadsheets...it?usp=sharing