Hanson recently commented on MetaMed on OB, but not here, so might as well quote some of it:

I wrote this post because I know several of the folks involved, and they asked me to write a post endorsing MetaMed. And I can certainly endorse the general idea of second opinions; the high rate and cost of errors justifies a lot more checking and caution. But on what basis could I recommend MetaMed in particular? Many in the rationalist community think you should trust MetaMed more because they are inside the community, and therefore should be presumed to be more rational.

But any effect of this sort is likely to be pretty weak, I think. Whatever are the social pressures than tend to corrupt the usual medical authorities, I expect them to eventually corrupt successful new medical firms as well. I can’t see that being self-avowed rationalists offers much protection there. Even so, I would very much like to see a much stronger habit of getting second opinions, and a much larger industry to support that habit. I thus hope that MetaMed succeeds.

This is a rather lukewarm and highly qualified endorsement, if you can call it that. The rest of the post is also a worthwhile read, as a critical assessment of LW cultishness:

As with religion, the main problem comes when a self-described rationalist community starts to believe that they are in fact much more rational than outsiders, and thus should greatly prefer the beliefs of insiders.

[...]

I’ve noticed a substantial tendency of folks in this rationalist community to prefer beliefs by insiders, even when those claims are quite contrarian to most outsiders. Some say that since most outsiders are quite irrational, one should mostly ignore their beliefs. They also sometimes refer to the fact that high status insiders tend to have high IQ and math skills. Now I happen to share some of their contrarian beliefs, but disagree with many others, so overall I think they are too willing to believe their insiders, at least for the goal of belief accuracy.