Well the Kenpachi thing is kinda weird in that Kaname's bankai doesn't let you use any of your senses and puts you into a void, but Aizen's makes you see, hear, feel, taste, touch anything he wants. So even that "let me get stabbed and then ill find you" trick might not work on Kenpachi, only Yama seemed to be able to tell it was the real him from the reiatsu in his sword.

I wonder how fighting with your eyes closed might affect Aizens zanpakuto? Would you still experience the sounds, smells, touch and taste of illusions even if you can't see them?