[AmbiDextrose]

No doubt. Everyone has limits even- a Visored Aizen would have an upper limit. But consider this- Orihime brought Tatsuki back when she was very close to death. Can she actually negate a person's death? That still remains to be seen unless someone can confirm that Tatsuki was actually dead when Orihime performed the Souten Kishun on her. If that is so, then it definitely raises her powers above those of the Shinigami because it violates reality (well, THEIR reality, to be honest) and the Shinigami's role in their universe.

Why would it matter that Aizen even becomes a Visored when Orihime has the power to negate his power (complete hypnosis) or even his very existence? That's probably why Aizen sought her out in the first place. Indeed, Orihime is shaping up to be a very important key in the events to come.