Great post! Some thoughts/experience I'd like to add:

1) How I got started. I began using a multiple-sub-agents heuristic for introspection when I stopped thinking of my mind as a point-mass. The brain has physical extent, and there even parts of my brain that I don't much identify with as "me" even though they affect my bodily functioning and behavior. I thought, how might those parts work? How should I treat them? And then, hey, why not treat them like people? They're made of brain, too.

By priors picked up from descriptions of various people trying this, you're reasonably likely to identify one of your sub-agents as "you".

2) "I am my executive system." To avoid losing or constantly changing my sense of self, and to maintain neutrality, I try to identify most strongly with my executive system (theorized by Miller, Cohen and others to operate primarily in the prefontal cortex). I think of "me" as a team leader who can coordinate the efforts of the rest of my various brain functions toward coherent goals that take into account their individual preferences. For example, sometimes I'll tell my entertainment-seeking-distraction function that it's probably in his best interest to let my productive-ambitious function work and build opportunities so life can be more entertaining on average in the future.

3) An honor system with signalling. When I strike a deal like that between conflicting functions or "sub-agents", I find it extremely important to honor the deal so the sub-agents continue to trust my leadership. After committing to this as a policy, I've found it unbelievably easier to negotiate inner conflicts, especially akrasia. For example, when I strike a deal between work and (other) entertainment, I commit to the entertainment agent that I will not procrastinate entertainment indefinitely. Then, I indulge on occasion as a signal that I will honor the deal more as I get older.

I don't know about the rest of you, but it seems to me that this "honor system with signaling" is absolutely essential to maintaining my own "inner order", and my quality of life has increased dramatically since I adopted it. Of course I can't be sure how it'd work for others, but it's an idea.