I just upgraded my Windows Logos4 to Logos5 using the starter package. In general, I've happy with the process, but do have one comment from a developer perspective:
Unless you are intending to allow users to operate two versions of the software independently, it's not a good idea to build the version number into the folder names. After upgrading to 5, I noticed that the install path still referred to 4. I checked the Add/Remove Control Panel and noticed that it only showed Logos 5, which was good, but what apparently happened as a part of the upgrade process was that the files in 4 were upgraded in place.
I suspect if I uninstalled Logos, and reinstalled from scratch, I'd see a folder called Logos 5, but of course that would lead to the same problem when 6 comes out.