I posted this at Google webmaster forums, but people seem to be more interested in moral posturing over there than practical discussion. Here goes:
I need to settle an internal debate at my firm. We occasionally spend a good bit of money to develop quality content for free resources on topics in our target market. These resource centers are the "link bait" for the Internet at large, and the resource centers link in to our sales pages. Our objective is for our sales pages to rank higher in Google. We have two competing theories as to how this should be done:
Theory 1: All resource centers should be hosted on the same domain as the sales pages, and link in to them. This enhances the ranking of the sales page in two ways, a) through a direct link from the resource center which itself has a lot of links from its inherent link bait quality and b) enhances the overall "authority" of the domain itself, also helping all pages on the same domain rank higher in general.
Theory 2: It is best to have the resource centers on their own domains, on different C-class IP's, and unique/anonymous WHOIS and have these link into the sales pages to help them rank better. The reasoning here is that the fundamental concept of Pagerank is that Google cares more about what others say about you than what you say about yourself. Thus, if our objective is to have the sales pages rank higher, we should create link bait on other domains/IP's and link in to it, so it appears to be a neutral third party link instead of an internal link Google will discount. The effect of "authority" domains is relatively minor compared to the direct benefits of multiple links to the sales pages from unique C-class IP's.
Which theory is correct and why? Any specific examples would be most appreciated.
Assume that the resources are equally attractive as link bait whether hosted on the same domain as the sales pages or on their own unique IP/domain. Assume anchor text is appropriate, all relevant related white hat type content.