I had the opposite experience with the latest version. The only thing that I needed to switch to ERA 6 is agent deployment behind proxy, which is solved with GPO install, and there is KB article for it. Once agent was set up, it was quite easy to switch all of the environment (100PCs) to newer versions, and update them to 6.1.2227 later. I must say that I really like policies, dynamic groups and tasks - I only had to update the task which was assigned to dynamic group to install the newer version of ESS, and all the stations got the upgrade automatically, and the policies were applied seamless