User blog comment:Lia Schiffer/396: The Bite/@comment-1248963-20100321070655

Devil Fruit Man, you misinterpretated Aizen's words. What he said was (quoting from Ju-Ni) "If one were to abandon all other abilities and specialize in only one thing then they would be able to oppose [Ryujin Jakka's] incredible power" with this he is referring to Wonderweiss and how he traded his speech reason, memories, feelings and everything else to have the ability to seal away Ryujin Jakka, not to himself. If Aizen had been talking about himself being twice as powerful as Yamamoto, just as you say, he wouldn't have needed to create Wonderweiss.