I was talking to a Kendo teacher about using two swords, and even though there is no real instruction he could give me he said that using a weapon in each hand usually does the same things for every user.
One it makes them robotic and forces them to use patterns over and over, it is the problem with having to coordinate the blades.
And two it decreases mobility, people just move ackward, kindof stiff while having no free arm to balance themselves.
One of the benefits though is that you would be able to defend yourself quite well with two blades, once you learned how to deflect attacks rather then absorb them.
I guess that there are exceptional individuals and all who these thing wouldn't be a problem for, I never really could "muster up" a straight face to ask him what he thought a Jedi would be able to do.