The two vendors I've already interviewed have been around for several years and their comments reflect their experience. What struck me the most was their evolution has been based on real-world experience that occurred before the Semantic Web was formalized by the W3C. Each founding team came with hands-on exposure to significant IT infrastructure problems and the recognition that Semantic Web technology is very well suited to solving these problems.
What's also come out of these conversations confirms that the differences will be in the details. Bear in mind I've only interviewed two companies so far and they don't compete with each other. But each one has taken subtle but substantial steps to differentiate the results their customers receive and likewise, the value of these results. Sorry, you'll have to wait for the report for me to clarify that rather vague statement.
More updates to come.