Support for earlier version of CUs and Exchange is there, just be prepared to update if your issue requires that you apply CU in order to solve it. As far as what Microsoft partners are saying ... well this is another topic. They seem to be confused with fundamentals ... Before you listen to any use your search engine ...
We seem to confuse functionality and security. You can have functional product that is not secure and I think this is what Brian is telling us here. Many customers already sacrificed security for functionality and stability. What good is secure system that is at risk every 3 months. This is why we have so many still running Exchange 2003, Office 2003 and Windows XP, or people stop applying patches, or use 3rd party product to secure Exchange. If you have LOB application that requires Exchange you are left with no choice really.
Few years ago I remember the notion of slowing down development and focusing on security and quality … I cannot speak for all IT Pros, but let us focus on security and Microsoft can focus on quality of the product. If you published documentation of changes/updates/enhancements like IBM does for Domino Fix Packs many of the problems could be potentially avoided.
Personally I don’t even understand why we complain … what other options we have?