LOL. I'm more annoyed at her reusing Greatful days~glitter~BLUE BIRD than her using Naoya the entire time.
That, I seriously have no problem with. I think it'll be fun. Like others have pointed out, it's just for a-nation, which is short anyway, as opposed to a whole tour or something. We've had nine other a-nations that have been extremely similar, so I think we can live with one that defies the norm
Basically I see it as Ayu doing something pretty new and different for her, and I don't mind Naoya's voice, so why not?

We won't know how good/bad it is until we see it anyway