Sorry; comes of butting into the conversation two years late -- hard to tell which way it's headed. Anyway, yes, a rational dictator would find it easier to impose, say, futarchy, than a coalition of rational voters would. There is an interesting question as to whether dictators are more or less likely to want to switch a rational system as compared to a majority coalition of voters. Dictators probably show more variation in their preferences than entire voting blocs do (although see http://www.cato-unbound.org/2006/11/06/bryan-caplan/the-myth-of-the-rational-voter for a strong argument that voter preferences do NOT exhibit much destructive interference), but dictators are also less likely to feel comfortable with (a) a major change that (b) encourages decisions to be made on some kind of 'expert' basis that is independent of the dictator's will. Even brainstorming in public about such a system could be dangerous to the dictator's continued enjoyment of the perks of power; once people start repeatedly applying the concept of "objectively right no matter what our Fearless Leader says," they're less likely to support the Fearless Leader.