This has only a little new intellectual content over the first metaethics post, but I wanted to revisit it:
Put succinctly - what's the utility value of an additional utilitarian ethicist?
Have you ever evaluated the ethical value, within your ethics system, of propagating that ethics system?
Take, for example, a greed-based hedonist; is such a theoretical hedonist best-served (his own prosperity being the measure of his ethics) by propagating his own ethics system, or would he be better served propagating an altruistic ethics system which he can better take advantage of?
This issue isn't limited to a subset of hedonists, however; consider a moral system which simultaneously values economic equality and has proscriptions against doing harm. Is it ethical to promote this ethics system to anybody who is better off than the global average, or in a country in which almost everybody is better off than the global average? The inherent guilt (and possibly hypocrisy) inherent to this ethics system reduces quality of life for most people who attempt to follow it.
The more limited the ethical system, and the more universal its scope, the more likely it won't have contraindications to its own propagation; ethical values with universal scope have particular resilience, such as "Justice," or "Equality," or "Liberty," or "Happiness," or "Life." Ethical systems rarely have singular ethical values, however; strict Randian Objectivism is one counterexample, choosing "Human Life" as its prime ethical value (for humans), from which others may be derived, but have no ethical meaning independent of that value.
Thus, there's some reason to believe Occam's Razor applies in metaethics; ethical systems which are simpler are more likely to be useful, because they're less likely to contradict their own use or propagation.