Let me start out by saying that I see more discussions about greenfield deployments of products than I do of migration/integration by vendors. Personally, I think there is no such thing as a greenfield deployment unless the organization is just starting out, creating a brand new data center, or perhaps has money to waste. In most cases, what is defined as greenfield is really just a grain of sand on an island of technology that still needs to integrate into the greater organization. As such, that integration should be the foremost thought when products are developed. But instead, it is not, and effort goes into becoming that island or into a replacement install that is still an island.