Have you read the Heaven post by denisbider and the two follow-ups constituting a mini-wireheading series? There have been other posts on the difference between wanting and liking; but it illustrates a fairly strong problem with wireheading: Even if all we're worried about is "subjective states," many people won't want to be put in that subjective state, even knowing they'll like it. Forcing them into it or changing their value system so they do want it are ethically suboptimal solutions.

So, it seems to me that if anything other than maximized absolute wireheading for everyone is the AI's goal, it's gonna start to get complicated.