I just realized something.
1. We know that Mace is a better duelist then Sidious.
2. We know that Qui-gon, Dooku, and Yoda where all equals in lightsaber combat with Mace at one time.
If this is so, I guess Sidious isn't so special with a lightsaber (obviously he makes up with this in force beastliness). Perhaps I'm thinking through this incorrectly, but does this mean that Dooku is a better duelist then Sidious? That just seems crazy to me.
Their facing Mace when he Mace couldn't use Vapaad at its best.
Vapaad is only really amazing against Dark-Side Users because it channels inner Darkness from the user and the opponent.
And Sidious is the darkest of them all.