We are looking to turn an internal tool we have developed into a Visual Studio Package that we would sell to other developers. The tool will impact the custom editor and/or custom languages. Visual Studio 2010 has redesigned the API's heavily to simplify much of the work involved for these types of integration but the key question we have is: What is the typical adoption pace of new Visual Studio versions? Is there any information out there on adoption rates based on history? How many shops are still using 2005? This will help us to consider whether to target just 2010 using the new APIs or whether trying to go back and support 2008 (maybe 2005) and testing it forward.