Board Thread:Theories and Speculation/@comment-31477926-20170702121758/@comment-7292165-20170820235510

@Namikaze

It is speculation. You're basically saying that just because nobody showed mobility with armored Susanoo, despite the situation not calling for the user to do so, means they are slowed down. And it's not about how Itachi would look running with armored Susanoo. Fact is, you have no proof. Nothing was ever stated in the manga or even in the databooks. They were never shown running or such because they never needed to.

P.S. I'm not saying Itachi should have went armored Susanoo as he was running towards Sasuke's side. I'm just saying that Susanoo does affect the user with weight, in a turn, their speed.