Code:
	Doublestrike	Bonus	Main hand	Off hand
No feats	0	 20%	100%		20%
TWF		0	+20%	100%		40%
ITWF		0	+20%	100%		60%
GTWF		0	+20%	100%		80%
Tempest I	0	+5%	100%		85%
Tempest II	0	+10%	100%		95% 
Tempest III	+5%*	+5%	105%		100%
LW Master	0	+20%	100%		100%
Wind IV		+10%	+10%	110%		90%
Zeal		+10%	+10%	110%		90%
Alacrity	+10%	+10%	110%		90%
* Only when wielding two weapons.

Wind is 2.5% per tier on both MH/OH as well Zeal and Alacrity give it to both MH/OH
Fastest could be 14Pal/6Rgr 110%/95% (harsh to build)
Ranger sits at 105%/100% (still best dual wielders except for above maybe)
Unknown how 18Rgr/1-2Mnk would work as 107.5%/102.5% possible to cap the OH at 100% no matter what
Rogues are 100%/80% could give rogues a level 16 or 19(feat) only special ability(Light Weapon Master) granting them 20% OH when they wield a light weapon in OH getting 100%/100%

This gets rid of Superior Two Weapon Fighting Feat still makes rangers the best dual wielders but makes everyone else close.

Are Zeal/Alacrity still giving bonus's to attack speed with MH or just to double strike and I don't know exactly how these are affecting 2H users that would be nice to add to the original post.