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Eyepaq, You do have a point (and thanks for pointing out how it's CTR that is affected and not buying behavior). That said, I do not think the drop would be anywhere close to even 20% given you are switching to a .com. The world is used to .com's. What would be affecting it initially would be the movement of link juice, but he is not going to drop right away with the old domain even with the 301. So, organically he will see some diminution likely, but I doubt a lot. Again, all of this MUST be weighed. There will be trade-offs. He must decide with the client what the tradeoffs are they want to achieve their goals. Best,

MozTrust isn't quite a measure of "trust" in the sense of link quality, per se. It was designed to mimic TrustRank, a factor we believe Google uses to supplement PageRank. What MozTrust and TrustRank (theoretically - we can't see in the black box) do is to take a set of trusted seed sites and determine how close in the link-graph any given site is to them. If your site is closely linked to sites like CNN and WhiteHouse.gov, for example (I'm honestly not sure what's in the seed set these days), you're more likely, on average, to be a trustworthy site. Of course, as with Google, this is just one of hundreds of potential ranking factors. One measure we've found useful in some cases is the ration of MozTrust to MozRank. If you have ton of raw link-juice (MR) but your trust level is very low (MR), then it's often a poor quality sign. We tend to use DA/PA more than MozRank these days, as they're based on a more complex model. Still, none of these factors look at the actual quality of the linking site or the "spamminess", per se. MR/DA/PA are primarily measures of the strength of your link profile, and MT is just one measure of potential quality. It appears that Penguin tweaked multiple factors in the Google algorithm and may even be use them in conjunction, so even if we saw Google's own data, we probably couldn't pin it to just one thing.

Having looked into this further, does the following code deliver? ErrorDocument 404 http://www.mydomain.com/ I am unsure, given your comment - "You must explicitly code 301 in your redirect or it is 302 by default and 302 redirects won't pass link juice like 301's will." Regards