Hitwise biased, but in which direction?

Hitwise is a competitive intelligence service that gives you insight into where your competitors get their traffic from and which keywords drive the bulk of their traffic from search engines, among other things. It comes at a price of course — to the tune of tens of thousands of dollars.

I noticed that in a post today Matt Cutts, Google engineer extraordinaire, made a small swipe at Hitwise in his review of the Compete search engine:

ISP relationships [buying user data from ISPs] can be a huge source of metrics bias. For example, some ISPs partner with Yahoo, and users on those ISPs are probably more likely to visit Yahoo. Other ISPs partner with Google. And savvy users that use smaller providers such as Covad or Speakeasy are likely not counted at all.

Because you don’t know which ISPs are selling user data to companies such as Compete or Hitwise, you don’t know what biases are baked into those companies’ metrics–and the metrics companies won’t tell you.

Touché, Inigo! (Matt Cutts’ regular blog readers will get that)

So my question to Hitwise is… If you won’t tell us who your ISP relationships are, will you at least reveal some of your biases? Like which search engine your biggest ISPs are partnered with?