Adam's right with that too - there is a different feel when using an all aluminum set-up, it just feels lighter and faster. I recently rode at the track with the Deda Newton Pista and OS Deda bars to match. It feels flexy in a sense but it also "feels" quicker if you know what I mean.

The oversized aspect makes up for the stiffness issue and in the end I think it comes down to feel and weight.