Here’s my two cents about Yahoo search.
We get a lot of traffic from search engines. So we spend a lot of time optimising our SEO and our site to make sure we have as much content in the search engine index.
When it comes down to the hard numbers of referrers, 98% of our search engine referrers come from Google and only 2% comes from Yahoo. (We have about the same number of pages in both indexes) Even though Yahoo is now powering the search for Xtra, the return for us is still so low. We’d rather spend our time and energy optimising SEO for Google we get far more return.
I’m sorry Yahoo, you don’t deliver the traffic to make it worth our while keeping our index fresh. As a result of poor click return, we restrict the rate that Yahoo crawler can access our site. (Not that they pay attention to robots.txt !) That way Google has more of our CPU cycles and bandwidth to crawl our site.