Yes, CEV is a slippery slope. We should make sure to be as aware of possible consequences as practical, before making the first step. But CEV is the kind of slippery slope intended to go "upwards", in the direction of greater good and less biased morals. In the hands of superintelligence, I expect CEV to extrapolate values beyond "weird", to "outright alien" or "utterly incomprehensible" very fast. (Abandoning Friendliness on the way, for something less incompatible with The Basic AI Drives. But that is for completely different topic.)

There's a deeper question here: ideally, we would like our CEV to make choices for us that aren't our choices. We would like our CEV to give us the potential for growth, and not to burden us with a powerful optimization engine driven by our childish foolishness.

Thank you for mentioning "childish foolishness". I was not sure whether such suggestive emotional analogies would be welcome. This is my first comment on LessWrong, you know.

Let me just state that I was surprised by my strong emotional reaction while reading the original post. As long as higher versions are extrapolated to be more competent, moral, responsible and so on; they should be allowed to be extrapolated further.

If anyone considers the original post to be a formulation of a problem (and ponders possible solutions), and if the said anyone is interested in counter-arguments based on shallow, emotional and biased analogies, here is one such analogy: Imagine children pondering their future development. They envision growing up, but they also see themselves start caring more about work and less about play. Children consider those extrapolated values to be unwanted, so they formulate the scenario as "problem of growing up" and they try to come up with a safe solution. Of course, you may substitute "play versus work" with any "children versus adults" trope of your chice. Or "adolescents versus adults", and so on.

Reades may wish to counter-balance any emotional "aftertaste" by focusing on The Legend of Murder-Gandhi again.

P.S.: Does this web interface have anything like "preview" button?

Edit: typo and grammar.